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I took down a 29 gallon tall tank I had setup. The substrate was gravel and sand on the bottom with a few plants. They never grew well, possibly due to the tanks height and weak lighting. The nitrates had risen to around 80ppm even with regular water changes, but it doesn't help that our tap water has 40-50ppm already. The fish were not doing as well as they should be and one tiny cory had died. Above are the test strips for both anoxic tanks, the top is the 20L the bottom is the 5.5 gallon. I moved 4 mystery snails and 6 neon tetras to the 20 gallon long where they joined our 5 black neons, 7 Julii corys, a betta, and 2 snails. The 20L was my first anoxic test and is running at under 20ppm nitrates, zero nitrites and ammonia, very hard, low KH, around 6.8pH, around 340ppm on the TDS meter. It has a slow plenum under gravel filter, an intank filter, and an airstone. It has some basil growing in the top as an experiment. I clear the center duckweed every other day, I just slide the foam dividers together and scoop it out. The top is a foam box with a reflective fabric made for hydroponics boxes this helps get the light onto the tank. The cutouts are terrible, I should have made them before I assembled it, but they work. I can tilt them to open them up and let it breathe. Now onto the nano tank with essentially zero nitrates. It's a 5.5 gallon with 6 green corys, 2 female guppies, and a mystery snail which all came from the 29 gallon. It uses a slow moving plenum, an intank filter, and an air stone. Its currently around 350ppm on the TDS meter. I filled it 75% with the old tank water the rest fresh, along with the plants, a big rock and a tiny section of the old tank's filter sponge. The next day I drained 25% and used water from the 20L anoxic tank and added the small pot which has a few scoops of the 20L substrate. The nitrites and nitrates registered for the first 3 days and have been clear for 3 days now. It has a deep bed of Safe T Sorb over an under gravel filter made from plastic fabric that has 7 holes per inch. I pushed the UG plate to the back so I can see inside a little. This picture isn't to scale, but the substrate is about 3 inches on average. The plenum is 7 squares tall (about 1 inch/25mm) with a 3/8" ID vinyl uplift tube (in the picture above it goes from over the 75mm down to under the 25 mm) it then goes to the surface, to monitor the flow. The plenum has some support plates holding it up but is otherwise open. It also has a small cheap intank filter. I blocked most of the lower inlets and cut a weir into the side. There is also a surface divider around the filter and the plenum uplift tube, it has some foam blocks to keep it floating. It's kind of ugly but it keeps the duckweed out of the filter and makes a nice clean surface. it seems a bit overstocked but so far they are all doing very well. I plan to add a male guppy and possibly a new betta.

I've started a few threads to get information and now I'm finally starting to work on it. However, I forgot to take pictures of the first day. I wanted to start this journal to document the process for my own benefit, but maybe others can as well. This stems from a desire to experiment with anoxic filtration, using a slow moving plenum as described by Dr Novak. A lot of people criticize his work without actually trying it. But I want to try it. I don't understand the science of it all, but I do understand anaerobic conditions is important. And if all goes well, a true nitrogen cycle can take place when nitrates are not just used by plants, but bacteria consumes it. If this is successful, my next experiment will be in a 20 gallon with shell dwellers. No plants, obviously. So before I mess with higher priced fish that are sensitive, I'll start with hardy fish. This 10 gallon will be planted with low tech plants. I don't intend to use ferts or CO2. Just lights 5 hours a day. The parts/pieces I'll be using: - 10 gallon aqueon tank that's about 5 years old - Safe T Sorb as a substrate - laterite - plants from the co-op: so far leaning toward wisteria, dwarf sag, and crypt lutea. - co-op USB powered air pump with tubes - air stone - plen plax UGF - fine mesh filter media bags - whisper 10 HOB with coarse sponge and ceramics - Dr Tim's for cycling. - fish; I'm leaning toward white clouds, but considering endler live bearers to satisfy my son's desire for color. Day 1: sift through safe t sorb. Pictures wouldn't be exciting anyway.

Hi all just wondering about your take on denitrification and the deep bed / biohome media / pellum creation - all involving the process of denitrification through a “complete nitrogen cycle” much conflicting info online from Jays aquarium / mankysanke / Dr Kevin Novak on one side and a number of forums and aquarium science.org lined up on the other - it seems fascinating but too good to be true - is it a busted myth - thoughts please thank you kindly stay safe Alex

I picked up 4 Mexican Dwarf Crayfish at the LFS 7 days ago and so far they are doing very well. Here they all are, the one coming out from the slate just molted. So far they've been peaceful with just a little sparring. They have plenty of places to hide, but they seem to be out most of the time. This one has a missing claw and 2 damaged legs, but its doing well. They like to get into the bubbles. Sometimes they jump in and fly up to the surface. They are in a 10 gallon tank with an under gravel filter, covered with 2 and a half inches of Safe T Sorb, and a slow moving uplift tube that cycles the tank about twice a day. I hope to create anoxic conditions. Its been running for about a month and a half, with other fish and snails, and the nitrate levels have already dropped below my tap water. The duckweed could be helping with that too. I put a cheap 4 gallon in-tank filter in to keep the flow low and more easily get the top fully sealed. I haven't figured out if I am going to put anything else in with them. I was thinking about trying some guppies or some other live bearers, so they have fresh meat to catch.

Well I done did goofed, forgetting to plug my canister filter back in after a water change, making it go anoxic for over a week. I thought I'd share my experience in case anyone else runs into the same or similar problem. I'll explain what happened, what I did to get out of it, and what I'd recommend for anyone with canister filters to do to prevent this. I'm not here to litigate whether or not canister filters are good or bad. This situation was 100% user error and can be easily avoided. Background: The aquarium in question is a 40 gallon breeder with a Fluval 206 canister filter with spray bar and intake sponge, as well as three sponge filters for additional flow and surface agitation. This is my fish-for-profit tank and is HEAVILY stocked with guppies and bristlenose plecos. I do water changes about once or twice a week and have a dense growth of hornwort and pothos to help me with water quality. It's a utilitarian tank, not a display tank, and I don't bat an eye when the water goes cloudy as long as the fish look healthy. The Event: I start my water change. As a pump withdraws water, I go underneath to unplug the canister filter, and I find that it's already unplugged. To make sure I'm not just having a forgetful episode, I feel the side of the canister filter to see if it's still warm; it's cold. I recall that the last water change I did was 8 days prior. Fortunately, I already know what that meant for the state of the canister filter. The Problem: Beneficial bacteria in your filters need oxygen from the water to process ammonia and nitrite. When you cut the flow of oxygenated water to them, they die after a few hours. Leaving your canister without water flow for a few hours won't kill your colony, but once you start looking at days without flow, there will be no oxygen left in the enclosed system. I knew that after 8 days, all beneficial bacteria in there would be dead. It'd be no use to plug this filter back in. I also knew that between all the fish waste trapped in the sponges in the canister, the now-dead snails that lived in the filter, and the dead beneficial bacteria and the anoxic conditions, it was highly likely I had a strong colony of anaerobic bacteria going in there, feasting on rotting organic material. I have a degree in civil engineering, and my senior design project was building a small scale anaerobic digester to process solid organic waste into useable methane. It was a fun but stinky project, and an experience that really helped me deal with this situation. I knew that the canister filter was now full of dissolved hydrogen sulfide gas (aka sewer gas) and other nasties. I definitely didn't want to plug the filter back in and have it dump that gas and decaying organic matter into my money-making aquarium. The Solution I Used: I disconnected the 206 from its hoses. It's really nice that Fluval's canister design makes this easy. Already I could smell the hydrogen sulfide gas from the filter. I then took a bucket, placed it underneath the detached hoses, and opened up the shutoff valve to back-siphon all the stagnant water out if the hoses. I did this until the water ran clear. This water also stunk of hydrogen sulfide. I started to attempt to clean the filter indoors....that was a very bad idea. That gas will stink up your home, make you want to puke, and it's very hard to dissipate. I've smelled open sewer manholes and wastewater treatment plants that were more pleasant. My advice is just take it outside asap. I'll post a follow up on how I cleaned up the filter and dissipated the gas from my home if people are interested. My Recommendations For Prevention: 1. Place your canister filter on a Kasa Wifi Timer. Schedule an "on" to recur every night at 1 am (or whatever works for you so it doesn't kick on while you're in the middle of working on the tank). That way, when you change water and turn it off, you can hit a button on your phone. If you forget to turn it back on, the Kasa will always kick it on at the time you set and you're not looking at days without power and flow. 2. If you're experiencing a prolonged power outage, take your canister filter media out and either place it in your tank or a bucket of water to keep it from experiencing anoxic conditions. 3. If you do notice your filter has been without power for a long while, don't immediately restart it. Assess the state of its contents (your nose will tell you if it's as bad as mine got). 4. Redundancy in your filter systems can save you headaches. My 300+guppies and 6 plecos appeared to have thrived despite the big canister filter being out of commission for 8 days. The sponge filters and plants in the tank kept it so I only had a small .25 ppm ammonia spike as opposed to something catastrophic. It also kept me from noticing that there even was a problem so there is that to consider.

Can anyone point me to some resources regarding deep sand beds? I have watched Cory's videos where he visits Ocean Aquarium and mentions deep sand beds, but I was hoping to check out some resources that give additional information. Also, for the process to work, does it have to ONLY be a deep sand bed, or can a deep gravel bed work as well?

Is anoxic filtration worth investing with an undergravel filter ? just started learning about it