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Muttley000's 270 Gallon plywood Sump

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Hi Jimmy!  Welcome to the forum. This Sump is still going strong!   This was my first time using epoxy like this.  I did not pour epoxy until the entire thing was built. The epoxy I used did not req

After a coat of exterior primer and 2 coats of exterior oil gloss paint for the outside the next step was a water test. No problems with leaks, and less than a quarter inch of deflection, which I was

Thanks for following! I would guess you could do glass a little bit cheaper to be honest if you are just talking buying glass and silicone. In my case I could never have successfully got a glass one

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Made a change to the sump.  Don't laugh, I needed it to be reconfigurable, and may not be done playing.  This is a 20" square I am hoping to grow Cheato in.  I basically made an eggcrate box, and put it in front of the last baffle before my pumps in the return section of my sump.  I am hoping to get a cheato ball to roll.  I used some corrugated plastic to make sides and direct the flow in a way to get a gyre type motion.  It took a couple tries but when I drop a clump of hair algae in there it rolls in a way I think will work.  I am lighting it with a Kessil H380.  I'll pick up a chain to hang the light then I just need to put the algae in.  I don't currently have any cheato, but do have a couple different kinds of caleurpa I can start with until I get some.  I wanted to take this step before putting the flucon in my system so I had some nutrient export while the algae is dying (hopefully) and the skimmer is off line.


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I was wondering if this sump was still going strong?  I'm having a custom tank made and I really want to build a sump using this method.  The only problem is I've never worked with epoxy.  It looks like you epoxied all of the wall layers before starting on the bottom of the tank.  Did you have to sand the bottom of the walls before adding the bottom layer of epoxy?  Does it hurt to make one thick layer instead of three thinner coats?  And finally, can I add bulkheads after the sump is epoxied; would drilling be a problem after epoxying the box?

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Hi Jimmy!  Welcome to the forum. This Sump is still going strong!  
This was my first time using epoxy like this.  I did not pour epoxy until the entire thing was built. The epoxy I used did not require sanding between coats unless it was more than 24 hours time between pours.  Because if this I did sand the bottom of the walls as high up as my epoxy was going, and then when I poured the 45’s in the corners I also sanded where they would be, just a light scuff to get the epoxy something to grab on to. I did it in layers so that if a bubble was entrapped there was zero chance of a leak path. I would ask the manufacturer about the thick pour but I don’t expect any issue there. 
When I did mine I drilled the bulk head holes ahead of time and oversized so I could put layers of epoxy on those edges So the wood was protected in the event of a bulkhead leaking. 
One tip if I were doing this again would be to have a hair dryer handy when you pour to pop the bubbles. I was blowing on them with my mouth and it did pop them but took forever. 
If you build one please share it!

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Thanks for the Info. I’ll definitely post here when I start. My sump will be 25”x60”x18” with a 40 gallon breeder inside for refugium and filter pad chamber. The water level in breeder will be at 12” and only 8” in a the plywood sump. With that being said it seems like I wouldn’t need to brace the tank and 3/4” plywood should do the trick without much bowing. 

2 more questions and I think I can start. Did you pour the 45 filets in one pour?  And how much left over material did you have?  I’m hoping I can get away with three gallons. But after calculating surface area I’m about 70% of yours. So I’d probably need five gallons, unless you had a lot leftover. 

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At that size and water level I doubt you will need any bracing with 3/4 plywood.  Do use a good structural adhesive for any baffles like Momentive.

I did pour the 45's in one pour and I had less than a gallon left when I was done but I did have a tape issue on one of the pours on the top edge (don't skimp on the quality of the masking tape and clamp boards on each side to reinforce!) that cost me about a quart of material.  I do feel I went thicker than planned and necessary on almost every surface though because I had plenty. The shipping is a killer on this stuff though so having to get more will offset any savings.  If you have extra do the bottom or inside of your stand.

Not sure where you are located but I have white pigment you can have if that is what you plan to use.  I would just have to check to make sure it was still good.

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When you tested your tank and had the 1/4" bow were baffles installed and how high was the water.  I don't plan on adding any baffles to the sump so I'm hope bowing wont be an issue. 

I was going to throw a 40 gallon breeder into the sump but now that I think about it, I could break apart the glass from the numerous empty tanks I have lying around and caulk that into the sump.  But I don't think I'll have a baffle fully across the short side of the tank, so no added strength.

I am going to use the white pigment as well, but I'm way out here in Northern California.  I really appreciate the offer.


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No baffles at that point and I filled it to the top!  Not sure what would happen over months if I left it that way though. 
If you observe bowing you could then add a brace like eurobracing on the long sides, but I see it very unlikely that will be necessary. The momentive bonds to the cured epoxy very well. 

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