270 plywood sump

I am building a large sump to tie all of my salt tanks together and accommodate 2 future similar size woody tanks. I am going with the pour method, using US Composites 635 epoxy. Size is 36 x 78 x 26 and it will take me a few days to get caught up posting where I am really at. Here are some construction pics.



And the epoxy being used

stempy said:

Nice, whats the system total volume of salt tanks?

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Thanks stempy. The total system volume will exceed 1000 gallons. I will be building 2 similar (hope to go a little longer) plywood tanks to tie in. Until they are built there will be 6 tanks ranging from 30 to 65 gallons tied in, and a 100 gallon Rubbermaid refugium. I will be building a large unlighted cryptic zone with another 100 gallon tub in the future also. I expect it to take a couple years to get all done. Sump will be way oversized until the first big tank is online! Thanks for looking!

stlbluesaddict said:

Subscribed!

Matt

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Thanks for following Matt!
Matt (my name too!)

coolkeith said:

Looking forward to see how you do this. Never seen anyone use the pour method for a fish tank. I know for tabletops that method is awesome. I see you're using birch plywood also. I was going to use BC plywood for my current build, but finding straight non-warping sheets without too many core voids has become problematic. So it looks like I'll be using birch also. Birch is just so much nicer to work with anyways. Just wish it was my initial choice. Trying to go the cheap route has turned out to be the more expensive in my case.

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Coolkieth, I will be sure to have the whole thing documented here! I did a lot of reading and consulting with successful builders before deciding the pour method was the way I would go. I will have almost 1/4" of epoxy on all surfaces that was applied in 3 layers, I expect the water test to be pretty uneventful, since I didn't even have any epoxy leaks in the first pour. If you look around in my build pictures you will see that I am lucky to have a well equipped shop. The birch ply was an easy choice for me. It's only about 40 bucks a sheet for the cheaper stuff, it's flat, and not full of the voids you speak of. Woodworking and furniture building is my other hobby, so I am excited to be able to mix the two. In fact I hope to possibly sell a few systems someday that are pieces of furniture instead of the run of the mill aquarium projects. Thanks for tagging along!

So here are some pictures of the pours going on. I started by building up the top rim. I will go back and pour this again one last time to cover the layers from the sides.


I didn't put pigment in the first pour of each side to save a few bucks. It was also easier to see bubbles when a different color was poured over the top of a previous layer. In fact a lesson I learned was that I wish I had done a gray pigment for the second layer and finished with the white on top. I picked white for the sump for visibility, I think it would look strange for a tank background.

One thing I forgot to mention is that there are small bubbles when the epoxy is mixed that must be removed. After pouring it on the surface and spreading it out I send a piece of rigid air line to blow on the bubbles. The CO2 in your breath makes the bubbles pop.
So after all the flat surfaces the corners must be poured. This means setting the tank up at 45 degree angles. Here is a pic that shows the sump in that orientation. I built a gage to help me get the angle right that you can see under the tank, it's kind of hard for me to move by myself!

And here is a shot where 3 corners come together.

With a build this small I determined I would not need to use wood fillets in the corners. The epoxy pour is about 1" wide per the recommendation of others who have built this way.
So, that catches the thread up to where I actually am. One pour per day is all I can get done. I got up early this morning and did the next to last corner. Hope to be able to water test next weekend, I really am curious to see how much deflection I will get at the top at the middle of the long edges with no bracing.