gardenman

When you say high tech I'm assuming you're adding CO2. There's a balancing act that goes on between nutrients (fertilizers and CO2) and light. You need enough light for the plants to be able to use the nutrients. I'd start out with the one Fluval and if you're not getting the results you want, supplement the lighting. I've seen people (Fish Boy USA on YouTube for example) with cheap LED lights off of eBay that grew amazing plants. I don't think he uses CO2 either. Growing aquatic plants is a juggling act between the right light, substrate, water conditions, nutrients, and the right plants.

The only real reason would be trace elements and that's somewhat iffy as a reason. Just topping off evaporation might refresh those enough. You could also just use a remineralizer at a reduced rate to supply those. There's lots of chatter about fish emitting growth restricting hormones that have to be flushed through water changes, but the folks at Goliad Farms have a long article about that. They theorize that live plants absorb those hormones, or neutralize them in some manner. Which kind of makes sense. I've got a horrifically overcrowded tank that's heavily planted and I've got an abundance of 4"+ neon swordtails thriving in it along with about thirty Super Red Bristlenose Plecos who are growing very well. It gets no real water changes, just topped off after filter cleanings when its canister filter tosses out a couple of gallons and water lost through evaporation. To say the fish are thriving in there is an understatement.

In my experience, aquarium plants do what they want to do and we're just along for the ride. I've got four planted tanks. The same substrate in each. The same water in each. Similar lighting (6500K LED) in each. And plants that thrive in one tank wither away and die in another and vice versa. Some plants are completely agnostic and thrive wherever I put them (Java fern, java moss, anubias nana petite.) They just grow and grow well in every tank. Duckweed does very well in three of the tanks, but not so well in the fourth. Red root floaters thrive in one tank, survive in another and die in two. Water sprite literally grows like a weed in two tanks, survives in one and dies in another. I brought in some water hyacinths to hold over the winter. They're doing great in one tank, hanging on in another and died off in the other two. Rather than chasing the water paraments I recommend buying an assortment of plants and seeing what does well in your tank. When you know what likes your water/substrate/light combination, you'll get a lot of it. My 30 high had an absolute jungle of jungle val. I added a Madagascar lace plant and the jungle val all melted away. It all died. I tried replacing it and no go even after removing the lace plant. Aquarium plants are quirky little things. I can grow everything in the way of terrestrial plants with no trouble. Aquarium plants are a whole different story for me. I marvel at the people who can get anything to grow in their aquarium. I'm not one of them. I can grow orchids just fine, but some aquarium plants just keel over within days of hitting the tank. The stuff that grows for me grows very, very well. I remove a bowl full of excess growth every weekend. I just never know what's going to grow in which tank.

You might want to look into drip irrigation supplies for gardens. You can buy drip emitters that will slowly drip water into your tanks. Be forewarned that they aren't always as precise as they claim to be. You'll want to test the real world flow rate yourself. Some are adjustable from 0-10 gallons per hour while others come preset for a specific flow rater (more or less.) Drip irrigation systems are pretty easy to adapt to aquarium water change systems. If your tanks have an overflow you can leave them running pretty much nonstop if you're using the 0.5 gallon per hour ones and you don't mind using 12 gallons a day per tank. You can get timers, filters, supply lines, pressure reducers and everything you need in some drip irrigation kits for a very small price. (Oddly enough even sites like Wish have some pretty comprehensive kits.)

There are lots of possibilities. Andy is right, your ph should be higher. A ph of 8.2-8.4 is pretty much the norm for a marine tank. As a rule, smaller volumes of water are harder to control than larger volumes. Three liters is a pretty small volume of water. When things go bad in a small volume of water they go bad quickly. A larger mass of water (5-10 gallons) might give you more stability. My house stays around 73 degrees, but it varies by several degrees. The temp will drop down to about 67 before the heater comes on and heats it up to about 77. It averages out to 73, but there are swings. In a big volume of water the swings don't matter as much due to the large volume of water. In a smaller volume of water the water can pretty much change with the temp changes. If your bowl finds sunlight at any point of the day the three liters might heat up pretty quickly in the sun. Even the light over it might help to cook the brine shrimp in a small volume of water depending on the type of light it is. You might also want to look at alternate feeding options. There are several brine shrimp feeding formulas out there, some of which use human baby food (pureed sweet potatoes and peas) as a base. It's possible your spirulina powder is still too big for them. Once a day is not feeding them often enough from what I've read. They require multiple feedings a day. Many small feedings are typically preferred over one or two larger feedings. If you can't be there all the time, some sort of drip feeder that lets a small volume of food mixed with your salt water drip into the tank slowly might be a good option. Something as simple as a small water bottle (the 16.9 oz size or even smaller) with a hole drilled in the top and a piece of airline tubing glued into the hole and then either an airline valve or a tight knot tied into the tubing to control the flow rate to just a drop every thirty minutes or so, might be effective. (You'll have to be sure you're not restricting things so much that it's preventing the food from getting through though. An aquarium autodoser, like the Jebao ones could be handy for feeding if you have one lying around. They can come on up to 24 times a day so you could schedule in hourly feedings for the brine shrimp. One end of the feed tube would go into what food source you were using and the other into your grow out container. Every hour it could administer a couple of drops of food to your shrimp. It could also be some impurities in the salt you're using. You never want to use iodized salt. Back when I kept marine fish I would find that if I bought larger volumes of salt mix, that I'd have to really stir them up before use as the salt in boxes or buckets would stratify in shipment. It's not as big an issue if the salt came in bags as they'd get tossed a round a bit more. Coarser grains would be on the top and very fine powders at the bottom. While they blend all of the ingredients at the factory, when they get shipped the vibration from traveling tends to shuffle the lighter stuff to the top and the smaller, heavier stuff to the bottom. If you just take what's on top, you're not getting a true mix unless you stir it up or use the whole volume at once. If you're using a marine mix a few tablespoons at a time, you might be getting an odd mix of ingredients.

There are two issues you'd have to deal with. The first is obviously nitrates. You could put the used water in a large tub/bin outdoors and fill the tub with something like water hyacinths or potted marginal plants like cattails that are very good at pulling nitrates from the water. Once you got the nitrates back down to a reasonable level you'd still have one issue though and that would be the trace elements. They'd be diminished. You could use one of the additives like those used for RO water in shrimp tanks to help replenish them however. Another option would be to collect rainwater to use for your tanks. Your roof likely sheds a ton of water each time it rains, enough to fill your tanks several times over. Collecting it and storing it could be an issue, but it's doable. (I use Rubbermaid trash cans and also Tuff Stuff 110 gallon stock tanks from Tractor Supply Co to collect rainwater.) Rain water tends to be a bit soft and acidic so adding some crushed coral or aragonite to the storage container would be wise. (Unless you're keeping discus, angelfish, or fish that like soft, acidic water.) Rain water needs to be filtered before use due to stuff on the roof mixing in with it, but it can be done. A heavily planted tank with moderate or minimal stocking can be maintained fairly long with no water changes also. I have high ammonia levels in my tap water, so I tend not to do large water changes and my fish are fine, but the tanks are very heavily planted.

My well water is off the scale in terms of ammonia. I never use it fresh from the tap because of that. I have a bunch of old plastic kitty litter containers that I use to hold the water until I need it and after a few days in the bottles it's more manageable. I suspect I've developed bacterial colonies in there that feed on the ammonia in the water. I also use Prime as an extra step just before putting it in the tank and there's never a problem. The kitty litter bottles last forever, are essentially free and would just go for recycling if I didn't reuse them to hold water. (I use Cats Pride Scoopable litter and it comes in 12 lb bottles for under $6 at Walmart and each bottle holds about two gallons or so.) The only real long term issue is nitrates. When you start out with a ton of ammonia, you end up with a ton of nitrates. Water changes don't solve the nitrate issue as you're just dumping in more when your initial ammonia levels are high. I keep my tanks very heavily planted to help contain the nitrates then toss out the overgrowth of the plants to physically remove the nitrates, but my nitrate levels are always higher than I'd like, but my fish do fine.

Assuming the lighting was normal the whole time, then something likely ate the algae in the water. Once whatever it was that ate the algae ate it all, they likely died of starvation and that could account for your nitrite/nitrate spike. The algae would be flourishing in higher nitrite/nitrate levels so the lack of algae rather strongly implies it all got eaten.

I'd be fine doing it with smaller tanks, but as the tanks grew larger, I'd get more nervous about it. Especially over the long term. Glass is an interesting material in that it's not truly a solid or a liquid but is an amorphous solid. The old stained glass windows in cathedrals are measurable thicker at the bottom than the top. The glass wasn't made that way, it flowed (very, very slowly) downwards due to gravity. You can even see this to some extent on more modern (1800s-early 1900s) glass. In a larger tank with not just gravity but hundreds of pounds of water trying to move the glass and just silicone holding everything together, I'd get a bit nervous about everything holding up well. The absolute worse place for a tank to spring a leak is in the bottom seam. Without a fully supported bottom you're putting more stress on that bottom seam. I've had two tanks (my 50 and 30 high) spring leaks in the last few years, but both leaks were midway up a side seam. That's not fun but even if not caught (and both were caught early) at most the tanks would have drained halfway. If it was a bottom seam, the tanks could have fully drained. Can you do support atank on just the ends? Sure. Do I recommend it? No. I want stability under my tanks and to take as much stress off the glass and silicone as possible. It's already got a tough job, why make it harder than it needs to be?

A lot of breeders will only sell males to prevent others from breeding "their" fish. It's been done like that for decades. I don't really blame them as some strains take decades to develop, but if you sell pairs all that work is gone as everyone can buy them, breed them and sell them without the investment of time and energy to develop the strain. If you do the math sometime the number of fish that can be created from a single pair of Endlers is pretty impressive. A typical Endler female has 10-30 babies at a time and can reproduce every 23 days. The babies can mature and start reproducing within about three months or so. If you assume a 50/50 mix of males/females than you're looking at 5-15 new females every 23 days. In ninety days when that first batch is ready to start popping out babies of their own and 5-15 females each pop out another 5-15 females so there are then another 25-225 new females that in 90 days or so will be each producing more babies. If you're a breeder and you sell pairs, you're creating market competition. If you only sell males, and Endlers typically only live 2-3 years, then you know that if someone wants another one just like the one they had, they can only get it from you. If you sell pairs/trios then in two to three years there might be a hundred people (or more) offering them, Even the holding back of males doesn't ensure you won't have competition as other breeders will pair your male with a similar female and through careful selection they can pretty much duplicate your line over a few generations, but it's a bit more work for them than just selling them a pair.

I keep a ten gallon tank set up all of the time and somewhat populated to use as a quarantine tank. It's got both a sponge filter and a small HOB. Right now it has an adult pair of Neon swordtails and three young neon swordtails and a youngish Super Red Bristlenose pleco. It's heavily planted, probably too heavily planted, I should thin it out a bit. By keeping the tank up and running I keep it cycled, the fish in there are doing well so there's no major water quality issue. The fish in there are all more or less expendable should something drastic happen with any new fish that go into quarantine. I've got over a hundred Neon Swordtails with them churning out more by the minute and over thirty Super Red Bristlenose plecos with my most prolific male sitting on a new clutch of eggs in his cave now. If you reset a tank each time you buy a new fish/fishes then something happens, you won't know for sure if it was a problem with the setup or the fish. By keeping the tanks lightly stocked with what are to me expendable fishes if need be, I can be sure it's not the tank or setup that's at fault. Any new fish that's small enough to go into a ten gallon tank for quarantine shouldn't bother the adult swordtails or the pleco. They're all pretty laid back fish that don't bother anyone else either, so it's a good colony to use to keep the tank cycled. Some infected fish won't display any outward symptoms as they've developed immunity to whatever they're carrying, so having a few expendable, presumably not immune fish exposed to them in a controlled setting will let me know if they're carrying anything. Many years ago (maybe 40?) I bought a very nice koi, about six inches long, at a very good price in a local petshop. It looked absolutely perfect, no outward signs of disease, but it carried something lethal to every other fish it came into contact with. I had it in a 29 gallon tank to start with and everything else in that tank died. I moved it to a smaller tank for treatment. I treated it for everything and it still seemed fine, but any fish it came into contact with died within a few days of exposure. Not only that, but even after a thorough cleaning and even bleaching of the tanks it was in anything new added would die. It wasn't just me either. The petshop had the same issue with anything that went into the tank had housed the koi. I finally just drained the tanks and parked them for a year and then when I reused them whatever had been there had finally died. I've got six red and six blue ramshorn snails coming as my latest order who will hit my quarantine tank for a bit to be sure they're healthy before getting relocated. I've got more than a few pond snails in there already so I know the tank can support snails with no issue. I'll leave the snails in there for a month or so and monitor the other fish to be sure they didn't bring anything then start moving them around. Having a few expendable fish in your quarantine tank can be helpful in determining if the new fish are carrying something they're immune to, but are capable of spreading. I've got tons of neon swordtails and bristlenose plecos so if I should lose them, it's not the end of the world. It's better to find out there's a problem in a small, isolated population though than in a bigger community.

There were a lot of products in the "good old days" that no longer exist. The old Aqua King and Super King filters were great. They made tank upkeep pretty simple as they were top down filters. You could layer filter material in them and then just peel off the top layer as it became soiled. Once every couple of weeks you'd have to stop the filter and plop in new layers of material, but that wasn't bad. There's still market for them. They moved a ton of water. A Super King is up on eBay right now for $400 which is an absurd price. They were well under $100 band new. There used to be a mesh diving bell (for lack of a better word) freeze-dried tubifex worm feeder that had a weighted bottom and a long string. There was either a removable bottom or a hole in the bottom (depending on the model) and you'd plop in a cube of Tubifex worms and drop it to whatever depth you wanted in the tank and the fish would crowd around to feed on the worms. Most of the Mom and Pop fish stores in my youth used to sell them out of a box near the checkout for like $0.29-$0.69. I can't find them anywhere now. They were great because you could feed catfish at the very bottom of the tank or hatchetfish or other top dwellers near the very top just by how far you let the feeder sink. The old Nektonics undergravel filters had a protein skimmer built right into the uplift tubes for the marine aquariums. They were pretty handy and effective. A lot of the old stuff is gone for a good reason, but there was some pretty good stuff back then also that's gone these days.

"Looking at a new tank and wondering if anyone has thoughts on making one from scratch as I want to do a 48 by 24 tank and not seeing one made for that size." Many, many years ago the University of Delaware put out a small booklet on marine aquarium keeping that included plans for a DIY undergravel filter. (The Nektonics UG filters were the rave at that time for marine tanks. If you kept marine fish back then, you needed a Nektonics UG filter.) Their homemade version of one used fiberglass or acrylic corrugated roofing panels that were cut to fit the aquarium. Then they used a fine toothed circular saw blade to cut slots in the filter plate for the water to flow through. The slots were cut across the corrugations, but just through the peak of the wave of the corrugation, if you catch my drift. Then they glued in lift tubes every foot or so along the back of the filter. They put spacers under the filter plate to ensure there was water flow under it and there you had a quick, easy, homemade UG filter that they felt was comparable to the Nektonics. I've been intrigued by the idea of building an undergravel filter that used split pieces of PVC pipe to create an air channel under the gravel. Kind of like a long open bottomed snake under the filter plate. In a smaller tank the airline would go down on one side of the tank into the inverted "U" shaped channel, travel along that channel to the outlet on the other side of the tank and then emerge through a discharge I like to think that would create more current under the whole filter plate and also provide more time for an oxygen exchange due to longer contact time with the water but I'm not sure if the newly inserted air wouldn't just rise above the air/water friction layer and zip out without disturbing the water under it. A way around that would be to use a long, very long, series of airstones spaced under the inverted "U" structures to agitate the water and inject the air at the same time.

You're talking substrate sifters and I'm thinking Geophagus or Malaysian Trumpet Snails, but you're talking about the inanimate kind. I far prefer the living types. They may not be as precise, but they're more fun to watch.

I buy the Aquaneat ones from Amazon and they don't need an airstone. They have an air distribution plate in the bottom that works pretty well. Over time the airflow will slow because they leave a long stem on the bottom of the air distribution plate that gets easily clogged. It's an easy thing to fix though. The following photos show how to fix the issue. That bottom weighted portion has two halves that can be pried apart. Then when you flip over the top you can see the long stem that bottoms out and ultimately blocks the airflow. I use an old pair of nail clippers to shorten that stem and then just reassemble everything and you're back to full airflow once more and forever more. It won't get clogged again with that long stem shortened. It's a fast, easy fix. The hardest part is prying apart that bottom shell. Just make sure you shorten that part that's on the bottom and not the top. I don't know why they make that bottom stem as long as they do, but that's the only real problem I've found with them.

That's a lot of plants in a 5.5 gallon tank. That's a lot of plants in a 55 gallon tank. You've got some very quick growing plants in Hornwort and some very slow growing plants in the Anubias. Dwarf aquarium lilies aren't all that dwarf. They're dwarf compared to a pond waterlily, but pretty big in a 5.5 gallon tank. You're making a tank that will require pretty much nonstop maintenance to keep the faster growing plants from choking out the slower growing plants. Can it be done? Yeah. It could work. I'd be more inclined to focus on fewer plants with the same rate of growth. All Anubias in a 5.5 gallon tank wouldn't be a bad idea. Your betta may need a weedwhacker to move around if you slip up on the maintenance for even just a few days with that many plants in that small of a tank. I'm weeding out duckweed, red root floaters, water sprite, and even java fern on a weekly basis and some of my tanks still resemble a jungle more than an aquarium. Your tank could look great when it's planted with those plants, but once established, yikes! Keeping up with it could be a real challenge for you.

In general, Silver Dollars and Tinfoil Barbs would be the first two fairly common, larger schooling fish to come to mind that would be relatively safe with an Oscar. They're generally big enough and tough enough to hang in there with an Oscar. A 320 gallon tank gives you a fair amount of room for them. If your Oscar is already a big Oscar the opposite direction might work also with a school of very small schooling fish. A big Oscar may just decide the small fish aren't worth the trouble to chase them down and eat them. And a lot depends on the personality of your Oscar. Some are pretty chill while others are more aggressive. Hiding spots tend not to be effective with schooling fish. Schooling fish tend to stay moving rather than hide. You more want obstacles for the Oscar to have to go around to catch them than places for them to hide. Of course, Oscars tend to like to rearrange tanks to suit their views on proper tank design, so that's not always so easy to achieve. You may set everything up exactly how you want it only to find your Oscar has completely different views on the ideal tank setup. Ironically enough, large goldfish, like those for ponds not the fancy ones, can make decent companions in an Oscar tank. Large Shubunkins, Comets, and the like can handle sharing a tank with a big Oscar pretty well. Try to avoid those with long flowing tails, but the bigger pond type goldfish can generally get along pretty well with an Oscar. Water temp and water quality becomes more of an issue, but they're possible tankmates.

As is often the case, it depends. There are some Oscars who are pretty mellow and there are some who are crazed killers. If you've got a pretty mellow Oscar who's just a happy go lucky guy who loves his pellets and doesn't care about anything else in the world, you could probably get away with it as long as the other fish weren't small enough to be eaten. In my limited personal experience (I've owned three Oscars) mine have tended to mellow out as they get older. A breeding pair of Oscars could be more trouble as they'd stake out a territory in the tank and guard it but a single Oscar in a 200 gallon tank with tankmates who were too big to be eaten, could work. I'd trust an Oscar more than say a Midas Cichlid or Red Devil as the others tend to stake out a territory and try to kill anything that enters it. In my personal experience, Oscars aren't as territorial. The bigger, older guys just largely go with the flow. Schooling fish like discus (and angelfish somewhat) could have a pretty good shot at survival as long as a pair didn't form and try to claim part of the tank as their breeding ground. If they did that and tried to drive off the Oscar, he might view it as a challenge and you don't challenge a big Oscar unless you're bigger and meaner and neither of your options are. Now keeping a pair from forming and trying to claim part of the tank may be your biggest obstacle. Fish are going to do what fish are going to do. Even then, with the right Oscar, a very mellow guy/gal, you might be okay in a 200 gallon tank. He might just give them that part of the tank and keep the rest for himself. Oscars aren't one of the most aggressive fish in the aquarium world by any stretch. They tend more to the mellow side than a lot of the rest of the cichlid world, especially as they get a bit older. If you have the right Oscar, you could probably get away with it. I had one that kept a pet goldfish for over a year. For whatever reason he chose not to eat that goldfish and they swam side by side for over a year. Oscars are pretty smart fish and you can't really predict what they'll do, but that's both their strength and weakness in your situation. With a lot of cichlids and other fish, you know the pairing you're looking at won't work. It might work with an Oscar, if you get the right Oscar. You just can't say for sure. I'd be more comfortable trying it with an Oscar than most other large, aggressive cichlids though.

If I was betting I'd say it was food related. There was a video from a discus breeder a few years back who raised his baby discus in a 125 gallon tank, but kept them all pinned into one small corner of the tank to get optimal growth. It was his belief that the baby fish would waste too much energy and burn too many calories searching for food in the whole tank if he let them roam free, so he kept them confined to a very small portion of the tank, but the tank still had a large water volume to dilute wastes. It was kind of weird seeing this big, long fish tank with about twenty baby discus all clumped together in one little corner of the tank. He was very successful though as a discus breeder and had huge discus on display. If your fish are roaming the whole 75 gallon tank looking for food nonstop they're probably not getting enough food to trigger optimal growth. The other fish may be out-competing them for the food also. Put it in human terms, if you had to walk ten miles each day before you got a meal, and then when you got there only a small amount of food was available and there were faster people than you racing for the food, you'd be pretty skinny. That could be the situation for your angelfish and parrot fish.

I'm using some 2 ft long Barrina 6500 K T-5 LED fixtures on my 20 high and they're really bright and good. They also make them in a four and eight foot length. You can daisy-chain them together. I'm using four on my 20 high and they light it great. The four foot long ones (ideal for a 55 gallon tank) cost under $50 at Amazon for eight of them (less than $7 each) and you can add or remove them as your light needs increase or decrease. All eight at once (they're reportedly 2,200 lumens for each fixture) would likely be too bright but you'd have that option. You'd want to build a hood for them to hide them and help direct the light, but they're a cheap and so far anyway, reliable option. I use a smart plug to turn them off and on.

Chew is kind of an iffy verb for fish. Oscars will mouth food, and create a mess as they process it, but I'm not sure I'd really call it chewing. Plecos kind of chew with their sucker mouths, but is it more chewing or scraping? Fish, even those with teeth, don't typically grind food with their teeth which is what we typically think of as chewing.

I bought six baby Super Red Bristlenose Plecos over a year ago from Catfishtown on eBay and he sent seven all of which lived. I put six caves (3 of 1" PVC with end caps and 3 of 1.5" PVC with end caps) and they've bred three times so far. and I've now got over thirty of them in my tank. Here's a photo of about twelve or so nibbling away on the tubifex worms pressed against the glass. They eat like crazy. Mine love meaty food (shrimp pellets and tubifex worms) and green beans. I put in about thirty or so shrimp pellets every morning and then three or four cubes of worms in the afternoons. Every other day they get some green beans and they go through a full can of beans in a week. They'd probably eat more if I put more in. They're really nice little fish.

I lost a big 22" Arowana and also an Oscar once to jumping where they jumped up, hit a solid glass cover and killed themselves. Conventional tank covers give fish next to no jumping room and if they're prone to jumping they will hit the glass, possibly injure themselves badly and even die. To prevent that I've started making my own tank covers out of the 3/4" PVC trim boards that are nine plus inches wide. Here are a few photos of the one on my 30 high. The PVC will never rot or decay and the fish get about 8" of jumping room before they hit anything too solid above them. I just use a sheet of clear acrylic atop the trim that I caulk in place. You lose a bit of light transmission by the lights being higher, but you save the fish. It's especially good if you're trying to keep butterfly fish, hatchet fish, archer fish, or the like. The PVC can be pricey but it works like wood, never rots, The surface of it is white which makes it a nice reflective surface on the inside and is paintable on the outside. Construction is super simple. You just cut the boards to the size you need, glue them together at the corners, add some trim PVC (I used PVC quarter round molding) to hold the acrylic and you've got a tank cover that's safer for the fish, easy to work in, looks good, and does everything you need a cover to do. And you can make it whatever size you need. I just use a saber saw to cut out the door to whatever size I want, add a pair of cheap small hinges from Walmart, use some scrap, leftover PVC to back up the door to block excess light leaking out around it, add a knob for the door, and it's done. The fish have room to jump and are less likely to hurt themselves jumping. They cost me around $50 to make depending on the price of the PVC at the time. I've got that type of cover on my 30 high, 20 high, 50 gallon, and 10 gallon quarantine tanks. I wouldn't use anything else these days. Holes for things like heaters or HOBs are easy to cut out using a saber/jig saw.

The type of Repashy largely depends on what type of pleco you're getting. Some plecos are largely carnivorous. Give them an algae based Repashy and they'll ignore it. My Super Red Bristlenose plecos are a combination of carnivore (they adore freeze-dried tubifex worms pressed against the glass) and herbivore in that they'll devour canned green beans. They pretty much ignore the algae in the tank though and leave that for me to scrape off. Some are more wood eaters and will ignore anything not wood based. A pleco isn't a pleco. Their diets vary from all plant to all meat to anything in between. Once you decide on which type of pleco you're getting then you can focus on the right type of Repashy for that pleco.

Parasites and pests are less of an issue when going from saltwater to fresh. There's not a lot that would transfer over. I would probably test them in fresh water for a few days. Fill a largish container with fresh water, check the ph before, plop the rocks in and then recheck the ph a few days later. If the rocks will affect your ph you should see a difference in a few days. I wouldn't worry a lot about salt leaching from the rocks as most freshwater fish have some tolerance for salt and may even find low levels beneficial. Depending on how large your large is, if you opt to boil them then a barbecue and a large metal trash can can be your best bet. As long as they don't affect your ph though you should be okay.