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Deep Reef journal

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I've always wanted a big tank.  But one thing or another has always stood in my way.  Cost (that's a big one!).  Space.  Structural support.  The prospect of moving in the near future.  You get the idea.  Well finally the stars have aligned.  I was able to get a decent sized tank!


My plans are to make this into a deep, rock reef à la Taiwanee Reef in Lake Malawi.  I now have the space to do this and do it right.  The tank is about 72"x30"x30" and about 280 odd gallons sitting on a powder coated steel frame.  There are decent sized openings to allow for scaping with fairly large rocks.


This project will be a slow burn.  First I need to do some plumbing.  The wall behind the tank is my boiler room - with a drain in the floor!  So, I'll be setting up an auto-water changer system.  Fill will be in  the tank, and drain via a bell siphon (that I'll need to build) in the final sump reservoir.  I'll also need to put in the PVC lines for the air from a linear air compressor in the boiler room as well.  Then I'll need to get at least the back and one side wall for the "cabinet" done before moving the tank out and then back into place.  The tank alone weighs 275#, so it'll be a project just getting the cabinet backing on.  The cabinet will be plywood that I''l paint black and hang from the steel frame with counter sunk magnets. 

Once that is done, onto the sump filter.  I'm having long conversations with some incredible folks about the design.  I think it's going to end up being an innovative sump design.  Stay tuned for that!  Then I'll have to add the acoustic paneling, which I add to all of my sump builds to help keep everything quiet.

After everything under the tank is done, then I finally get to worry about the tank.  The current plan is to use some local limestone to build a reef in the tank with some granite derived sand in between.  Flow will be a challenge, but I suspect reef pumps will be involved.  I have lighting plans.  They involve soldering my own COB LED lights and running strip LED lights to attain a deep water shimmer with loads of blue saturation.

For stocking, I have only one fish in mind: Chindongo saulosi (syn. Pseudotropheus saulosi).  I hope to get fish from at least three different distinct sources and get a genetically diverse breeding colony going.  Why?  Because I like having colonies of a species.  Sorry the justification wasn't more interesting that that. 

Anyhow, I hope at least a few folks will be interested and follow along with me on this journey.  Thanks for looking!

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It's going to an interesting project i just started reading a.d koning Malawi cichlids in there natural habitat lots of useful information if your doing a Malawi biotope


Edited by Colu
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13 hours ago, Colu said:

i just started reading a.d koning Malawi cichlids in there natural habitat lots of useful information if your doing a Malawi biotope

Great tip!  Thanks!  I'll see if I can find a copy.  I'm not doing a biotope per se.  I'm certainly not looking for Malaŵi (I've decided I like that accented w!) snails for instance.  But I am absolutely hoping to create something the evokes that deep rock reef look in the lake. 

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  • 2 weeks later...

***Fair warning: this is a long update with not a great deal of physical progress***

I've begun the process of outfitting my Deep Reef tank.  There are so many things to do, and the scale for this size of tank means I am not sure I am going about this in the right order.  But, because I like to think about filtration (some might say too much), I'm starting there.

The first thing I needed to do was to figure out just how much water I am dealing with.  So here is a quick run down of the tank (this process works for any tank of course):

Acrylic thickness - 0.75”
Internal length - 70.5”
Internal width - 28.25”
Internal depth - 28.75”
Calculated volume max ~ 247.875406 gal
Depth of weirs - 1.5”
Internal tank depth less weir depth - 27.25
Max water drain when pump stopped - 13 gal
Functioning tank volume ~ 234.942776 gal
Flow rate x 6/hr ~ 1,4010 gph (23.5 gpm)

With all that known, I could set about figuring out the sump size.  I have a tendency to err on the side of more sump than needed.  This is especially true for messy fish and where I have no plants in the display.  Both will be the case here.

Perhaps more importantly than the size of this sump, is the design.  I've been having wonderful conversations behind the scenes here with a couple of very thoughtful and knowledgeable folks (you know who you are) about filtration.  What has come out of those conversations is the design I will present here which I call a "Sock Last" arrangement.  I've kind of decided filter socks are amazing!  But they are placed in the wrong location, leading to the major complaint about them that they are a lot of maintenance because they clog quickly.  I've found this to be true on the sump I have from a kit which is the "Sock First" arrangement where the water from the overflow goes directly into the sock.  With that design you funnel everything coming out of the tank through your finest filtration.  That is a recipe for quickly clogging the filtration and high maintenance.  I liked @Cory's setup with the multiple vertically oriented layers of diminishing porosity of foam.  But, just I couldn't give up my socks.  They are so easy to change out, and they filter to the micron level. 

So here is the basic schematic of what I have come up with for my design:


The flow is designed off the principle there should be a "dirty" side of the sump and a "clean" side that is where you draw from to return to the tank.  This design puts a lot of focus on the order of mechanical filtration. 

Tank 1 is the "Refugium Separator" which serves two purposes.  The first is to have it act as a settling sump where the largest waste can settle out and rest on the bottom.  To facilitate this the water will enter below the functioning water level of this tank (which also serves to cut down on noise) and then flow upward through physical baffles.  As the current slows the large material can settle, with the cleaner water moving upward and out to the next tank.  This tank will also act as a refugium because there are no plants in the display tank.  This should allow for some nitrate capture and hopefully prevent spikes of unwanted nitrogenous wastes (I've got an experiment planned to determine which plants I would like to use for this purpose - I'll do another thread on that when the time comes).  The physical baffles will hold the plants in place, and their mass will act as a secondary baffle for the separator function.  I'm hoping I get a synergy out of these two functions.  This tank will need to be regularly maintained by removing excess plant biomass and sucking out the sludge with a shop vac.  This is the dirty side.

Tank 2 is the "Moving Bed BioReactor" or "MBBR" section.  These tend to be incredibly efficient and self cleaning bioreactors (and all of our "biofiltration" devices really are bioreactors that oxidize N wastes to less toxic forms).  Here the water will come in directly from the overflow into the churning mass of media.  There might still be some particulate matter in here, but the grinding of the media should help keep the particle size down.  To get the water into the next tank, it will have to pass through a barrier to prevent media loss and then a layer of foam which act as mechanical filtration and can be changed out.  I believe I'll need this layer to catch any biofilm sloughed off from the biomedia as time goes on.  Otherwise this section should be largely maintenance free.  The air for the MBBR will come through a PVC line in the wall behind the stand.

Tank 3 is the "Reservoir Return" tank.  Here I need a tank large enough to hold the water that will drain from the display when the pumps are turned off.  The water will come into this tank after the foam filtration and then pass through the socks as a final mechanical, polishing filtration.  Hopefully this will mean the socks function as a micron filter should and be less of a hassle.  After the socks there will be a heater and return pumps.  The socks should keep the rest of this section fairly maintenance free.  This is the clean side.  I'll also have room to include a hydroponic bell siphon to have an automatic water change system for this beast of a tank.  That will live in this section as well.  Lastly, I am working (with help) to see if I can build a proper foam fractionation system for my aquarium.  They are called "protein skimmers" the saltwater side of the hobby, and are used at large scale quite successfully in ponds and some aquaponics setups.  I'd like to get it working on an aquarium scale.  We'll see.  But at least there is room for me to play with that project here.

So that is the schematic and rational.  Here is a photo of the tanks I've found to try to accomplish this:


I'd wanted to make this entirely out of easy to find totes and bins so others could easily adopt this system if it works out well, but because of the size of the final tank that I needed, I did end up having to go a little specialized for that one.  I'll have to build the floor for the stand, and raise tanks 1 & 2 to get the height I'll need for the gravity feed on those, but these are the basics. 

On the left there are two, 13 gal, hydroponic grow-buckets.  I wanted something black so I could contain the light for the refugium in that first section.  I'm not sure I'll need both, and I'd prefer not to have to plumb them together, but the turnover in each bucket is going to be faster than a minute and I need to make sure the current is slow enough for the separator function to work.  So that's a bit of a question mark still.

The MBBR is just a Rubbermaid Brute tote.  I've used them in the past and they are cheap and effective.  This is the 20 gal version.  The lid is drilled from it having been used on another project as a water tank, so I'll have to replace that bit.

The Reservoir Return tank is a 42 gal RV water tank blank (i.e. no holes).  Because I am using it on its side, creating a lid for it is going to be a challenge.  I'd love to get input on that.  From the photos, I hadn't anticipated such deep channels on that side.  Oh well.  But, I do want a lid.  I always use tight fitting lids to reduce evaporation on my sumps.  It can get out of control in the winter here otherwise.  The purple circle is just the bunged up hole from production.  Just thought I'd explain what that was. 

Anyhow, that's the update for now.  Like I said not a lot of physical progress on building the air system or the stand covering.  If you've read this far, I'm impressed!

Thanks for looking!

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40 minutes ago, OnlyGenusCaps said:

The Reservoir Return tank is a 42 gal RV water tank blank (i.e. no holes).  Because I am using it on its side, creating a lid for it is going to be a challenge.  I'd love to get input on that.  From the photos, I hadn't anticipated such deep channels on that side.  Oh well.  But, I do want a lid.  I always use tight fitting lids to reduce evaporation on my sumps.  It can get out of control in the winter here otherwise.  The purple circle is just the bunged up hole from production.  Just thought I'd explain what that was.

Are you set on a single lid? Because you could consider cutting the two center pieces at the top area only, therefore using the edges as support (or leaving the channels too!) and using the cutout as a lid by. These silicone strips work great at making tops as aquarium lids:


Using them on both edges will give the lids more stability as well as help with evaporation. 🙂


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3 hours ago, eatyourpeas said:

Are you set on a single lid?

Not at all.

3 hours ago, eatyourpeas said:

Because you could consider cutting the two center pieces at the top area only, therefore using the edges as support (or leaving the channels too!) and using the cutout as a lid by.

That's an idea!  I need to figure out how I'm doing my socks too.  Do I just drill in bulkheads with down pipes in the first section?  That could work.  The hitch is that the automatic water changer (AWC) will cause the level of the tank to fluctuate by several inches.  This is going to either make the socks quite noisy (something I really want to avoid) or potentially overflow them, which seems like a bad idea.  I'm thinking the most straight forward thing will be to set them on a float system.  That way they come into the water at the same depth all the time no matter where the AWC stops, reducing noise and preventing overflow.  Not to build such a thing...

3 hours ago, eatyourpeas said:

These silicone strips work great at making tops as aquarium lids:

Okay, that's brilliant!  I would never have thought of that, and I'm sold on using them for my lids.  Thank you! 

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  • 1 month later...

Today I ran out and picked up what might turn out to be a first load of rocks for the Deep Reef tank.  This is about 400lbs of rock:


I went to a local landscaping supply company to get them.  For folks who have not sourced rocks from landscaping places before, I would absolutely encourage you to do so!  I walked out with 400+lbs of rock for $21.  I think the rocks were priced at about $5.25/100lbs.  It's vastly less expensive than buying rock from a LFS. 

Now, I'm a supporter of buying from LFS when it makes sense, but this local business is way less expensive and had more, and different, options.  The other thing is you can setup a tank that is unique and local.  Rocks don't tend to be shipped far because of the cost, so what is available in your area will be very different than what is in mine (unless you are located close to me, of course).  I bought "rip rap", which is a name for cheap local stone.  It is used in drainage culverts, and to prevent erosion in various places.  In my area, it tends to be local limestone (which is what I wanted), in your area it may well be something different.  Of course there were other options of different sorts of rocks available as well.  

I certainly don't want to suggest that folks who want seiryu stone or dragon stone are doing something wrong.  If there is a look you absolutely must have, pay for it.  I did the same with my Pseudo-Salt tank.  Paid way too much for the rocks that gave me the very specific look I wanted.  I suppose I just think this is an under utilized resource for aquarists and provides the opportunity to scape a tank in unique ways without spending a lot.

That seems like a decent update and rant combo for the day.  😃  Thanks for looking!

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  • 2 months later...

Progress on this one has been glacial at best.  It's been loads of background work to get the systems setup to make maintenance of this monster possible.  Or at least compatible with my life.  So, the central air line I've put in my house is really to drive the MBBR for the sump on this tank.  Sure, it;s useful elsewhere, but this is the main reason.  Also, the auto-water changer system I've put in is primarily for this.  Yes, it;'s now running my tanks on my rack too, but it is the desire not to haul 25-30 gallons a week in water changes that caused me to decide to put that system in.  Essentially, there has been progress, but not much of it visually obvious in the room with the tank.  This lead my wife and mother-in-law to want to know "when will there be fish in there?"  This was my response (hastily written in poor handwriting):


I also got another $18 worth of rocks for the tank.  That should do it once added to the previous load.  Here is the second batch:


Otherwise, I think this is a winter project.  Which is nice to have.  Winter can be long here.

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  • 4 months later...

Finally, I have restarted work on the Deep Reef tank.  The tank is so big, it's kind of intimidating to work on because the cost of mistakes will be so great.  But, I've got to get over it, and get at it. 

To start with (besides all of the behind the scenes ordering of materials), I wanted to get the skin put on stand frame.  Perhaps this seems an odd spot to start, but it means I can then line the back up with the wall when I need to drill through for the MBBR air supply, and I can line the stand walls with acoustic foam, which I like to do to lessen any noise from the sump.  Speaking of...  I'm impressed by just how compact the foam is when it arrives.  Check this out:


The foam came in two equal packages like the one on the right.  Left is how much it has expanded after a day.  Just amazing!  The other odd thing is that it feels rubbery when it first comes out of compression, but then hours later it begins to feel like regular foam. 

So, I want to skin the frame of the rank, which is power coated steel, to make the sump less obvious both visually and acoustically.  It'll also keep the evaporation down a bit.  At first I wanted to use plywood, and counter sink some strong magnets into it to hold it to the frame.  I even did a test piece:


A problem quickly showed itself though.  The plywood is really heavy!  I would need to order some pretty good sized magnets to hold the weight of the wood up.  Now, I have 60+ smaller, good quality neodymium magnets around.  After a trip to the big box store, I found thinner, and frankly much nicer looking stuff.  Can't recall the name.  But here it is leaning in place on the tank stand:


The next step will be to get the magnets epoxied onto the boards, and figure out how many I need to hold this much lighter stuff onto the frame.  Then, once i get the other boards cut, it's craft time, using the hot glue gun to glue the acoustic foam all around the inside! 

I'm hoping for more frequent updates as this work progresses.

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Remember how a few posts ago I was thinking about how I might mess this up.  Well...  At least in a small way - accomplished!

I had some time on my hands in an actual block this week and thought I would take advantage of it to work on this tank.  Everything takes time with efforts at this scale I am finding.  No "I've got 10 minutes, let's get something done" going on here.

I decided with this windfall of available time, I should get the magnets attached to the boards I'd cut, attach the acoustic paneling (really just crinkle cut foam, but whatever) to the first panels, and then cut the remaining necessary panels.  Good list of goals.

So, I penciled in where the opening is between the steel for the two panels, being careful to mark their proper positions.  I decided use epoxy on the magnets.  Got Gorilla Glue brand after watching a video on epoxy tests on the YouTubes.  Sure, not the strongest, but each magnet is small, so I should work.  Here is the result, see if you can see my mistake:


Now, I can't be sure how many magnets I'll need, but one at each corner seemed a good place to start, and with the pull strength of these little guys, it should, technically hold the weight.  That meant, I ended up with two panels that looked like this:


Feeling chuffed at my efficiency, especially with epoxy that I have little experience with, I started in on gluing the acoustic tiles (again, just fancy foam).  I've done this before and know hot glue works well so...  Craft time!  I was making great progress, but every time I bumped the epoxy it was still really liquidy.  Like when the threads of hot glue draped on it, they would embed and I had to carefully pull them out. I checked the epoxy label and sure it was quick set, 5min, but takes 24 hours to dry.  Okay, I'll just be careful.  I got all of the foam glued down, which too some time.  Frankly after slowly squeezing hot glue around panel edges, I was done after two of these.  But, I think they turned out fairly well:


Off I went to cut the remaining panels. When I returned I set the panels off to let the epoxy dry somewhere safe from little fingers. My kid's, not mine. After 24 hours the epoxy seemed like it had cured, though didn't end up as rigid as I was familiar with for what I think of as "epoxy resin".  I didn't think much of it as my trusty video has explained that quick set epoxy is not as rigid or sturdy as whatever the other category is. Real epoxy?  Slow set epoxy?  Epoxy classic?  Whatever. 

I gleefully popped the panels on and off the steel frame, and it worked!  I worked beautifully!  They looked great when they were up. Held well enough with just 4 magnets, and popped off easily.  Who could ask for more?!

Cut to the next evening.  I wanted to show this off to my wife.  As I approached I noticed that the boards weren't sitting smoothly against the frames at a couple of corners. I announced the boards must be warping because it is so dry (this might continue to be a concern as our basement is like 20%RH all winter and 100%RH in the summer if the dehumidifier goes off for various reasons).  Figuring all I needed to do was add a few more magnets to correct  the situation, pressed on with my demonstration.  As I pulled the panel away from the frame there was a loud "CRACK!!!".  Already I suspected this was not a great sign. 

For those of you who saw my mistake right away this will not come as a surprise, but when I finished pulling the panel out,  the magnet remained.  Stuck firmly to the frame.  You see, I had been concerned about the thin magnets (which in my defense are brittle) would crack snapping against the frame over repeated use.  So, I figured the solution was to cover them with a thin layer of epoxy.  This turned out to be a mistake, mostly because the epoxy never fully hardened.  I'm guessing because I didn't mix it well?  And then only hardened under pressure between the magnet and the steel.  🙄  Figures.

For those of you familiar with epoxy I have a few questions for you:

1. Is there a solvent you can use to remove epoxy?  Specifically to salvage the magnets I've already used.

2. Is there an epoxy or glue I should be using instead of the Gorilla Glue quick set epoxy?  Or do I just need to be better with what I have?

Thanks in advance!  And also, if you've read through this whole thing, I'm impressed! 

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Acetone should do it.

Hate to say it, but I was cringing the whole time having a pretty good idea what was coming. 😅

I'm used to working with epoxy as radio control planes used to be a hobby of mine. For my 150g tank, I actually did a plywood epoxy bottom. 

Edited by Vanish
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The tale of the failed epoxy has turned into a bit of a snag in working on the paneling.  If you really care, you can check that out here:

I've decided I do not want to let that hold me up.  So today I purchased $300 in plumbing fittings.  🙄  Big tanks = big bills.  This will get me started on the sump build.  For some reason the photos of the sump arrangement in my previous post are now unavailable.  🤷‍♂️  I did replace the first containers anyhow, making it a bit different regardless.  Here is the basic arrangement:


It will consist of 3 RV water tanks linked with PVC.  The first two will be constant volume containers, and the third will fluctuate with the return pump going on and off as well as automatic water-changer.  Once I get working on the plumbing I'll go over details of the flows and purposes of each chamber.  But for now, I need to decide how I want to get into these tanks so I can get started!

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Today was a momentous day for me.  It was the first day I've ever climbed into one of my tanks!  I needed to get the overflow drains in today, and so I had to get on a ladder and climb into the aquarium so that I could get the pipes measured to be cut to the right length for the drains (I'm doing a Herbie style drain set up in each of the overflow weirs).  It was surreal sitting inside of the tank and realizing "this is what my fish will see when they are swimming around in here!" 

Productive day though.  I got the drain lines cut and in, as well as the Loc-Line returns installed.  Basically all of the stuff I need to crawl into the tank for.  For now...

In the process I learned that anything that you have to do while working from inside the tank takes far, far longer than you expect!  Think about how annoying it is when you forget something you need at the bottom of the ladder?  Well, add crawling in and out of a tank lid to that.  Makes me wish I was more organized.  I also learned that I don't think I ever want a tank much deeper than 30".  When you have to reach the o-ring for a bulkhead at the bottom of an overflow weir, 30" is deep enough! 

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