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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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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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