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Acrylic tank busted. Time to build a new River Tank.

118403 Views 403 Replies 64 Participants Last post by  tylerj
Yep. My 90g river tank is done after about 3 years in use. It never leaked, but I noticed some crazing in one of the corners, then I looked closer and the whole side gave away from the perimeter bracing. The cause of the failure was probably warpage. I used 1/4" continuos cast acrylic instead of cell cast acrylic to build this tank because that was all I could get my hands on at the time. I guess the key to building acrylic tanks is to use CELL CAST like Featherfinfans article suggests.

Anyways, this is good news because I've been itching to build a new tank for awhile now. This time I'll try not to skimp on materials.

Here's my plan right now for the new tank-
It will be made out acrylic, foam sheets, and plywood. Also, instead of doing a foam/cement background, I'm going to build a foam/cement midground. This midground will be a massive island. Having an island will act as a partition so that the water can have true unilateral flow. To get this river type flow, I'll point all the filter outlets in a clockwise direction.

Here' my blueprint :D

I'll start a cut-list and estimate the costs now. Hopefully it will be within my budget so I can start soon. I could just repair the old tank for real cheap, but that wouldn't be nearly as fun.
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Are you going to re-cement the separation? 1/4" for a 90 gallon is rather thin.
I'm not sure yet. I'll probably try. I could add more bracing for reinforcement. The tank is only 12" high though. There was 2 inches of sand in the bottom and was filled about 1.5 inches from the top. Actually volume was more like 70 gallons.

I think another factor in what busted this tank is that the the canopy hood was not laying flat on the tank. It was accidentally sitting on a filter pipe. This created a pressure point on the perimeter bracing. A water-bridge was also sitting on the bracing. If it was a case of water pressure being to great for the acrylic, then the seams would of busted on the bottom, not the top. The bottom seams look fine.

I doubt I'll use this tank full-time anymore. I dont have much use for it if I build my dream tank. I might fix it, then sell it on ebay. It would make a real nice reptile tank.

The tank is 72" long, 24" wide, and 12" high.

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it'll make the perfect sump for that monster river tank, don't get rid of it, big honkin mechanical surface area, and lots of room for bio and even a refugium section.
Thanks Mikmaze. That is a great idea to use it as a sump/refugium. I'll just fix it real good so that it won't bust again. I'd have to make the stand / tank wider so that this old tank will fit underneath though. So now the main tank is getting bigger. It's now 233g plus 90g from the sump/refugium = 323 total gallons. I'm liking this idea alot. Thanks again.

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you are quite welcome, if ya need any more help spending your money, I'm here for ya :D
Will the tank be viewable from both sides? I so the Island thing is pretty cool - but if not I would go with the background myself... You could still create a river effect if you had the inlets at one end and the returns at another...
I'd like to get some more idea's to build the Island.
Most importantly, the island will be mostly hollow with caves for the my clown loaches. I'll probably build it like a sandwich. I'll start with a sheet of styrofoam, then I'll use twisty ballons as a mold for the caves in the middle, then spray some Great Stuff foam all around the ballons, then use another sheet of styrofoam to top it off. When the foam spray hardens, I'll pop the ballons and start carving my underwater mountain. Then I'd get my sawzall and cut the thing into 4 parts so I can get the thing inside the tank.
I was thinking I'd use cement or drylok to cover the thing. I've got alot of quikrete cement color's. Can I add these colors to Drylok? Can I add sand to Drylok?
I'd like to use magnets to hold the island down underwater to keep it from floating. I'll have to imbed the magnets into the bottom of the island somehow. Maybe some real thin acrylic can be cemented over the magnet onto the bottom of the tank to make that near permanent. I'm out of thoughts for now.
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Just viewable from 1 side and maybe from the top. For now it's going against a wall. I figure I can hide all my filter inlets/outlets behind the island. So it's not wasted space.

Just putting an inlet on one side and an outlet on the otherside won't give you true unilateral flow. There are too many cross current's no matter how big the water pump is. I think the island and the rounded corners is key for true unilateral flow.

I took my idea from this segmented tank-
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I'll try to get a quote on some Acrylic tomorrow. I hope my supplier has atleast 10ft sheets and that I can afford them, otherwise I'll have to build the tank in 2 pieces.
No luck on getting 10' sheets of acrylic.

3/8"x96"x48"' sheet of Acrylite GP Cell Cast acrylic costs $195 per sheet out the door.

1/4" x 48" x 16" plate glass costs about $43 out the door.

I''ve drawn out plans, have cut-lists, and cost estimations for acrylic and plywood tanks. I'm not sure what I'll do yet, but I'm still leaning on acrylic.
Sorry to hear of your problems Keith, It's a shame how high Acrylic pricing is these days. Just a couple years ago I was getting 1/2" Plexiglass G (CellCast) for $138 and that included up to 4 cuts.
138 I wish. I just got quoted for $208.00 for a 4 x 8 sheet of cellcast. I am planning one of these tanks out now using your article FeatherfinFan. Not sure on the dims butt I am kicking around a lot of numbers. Any warnings lol..........
I think I'm going to build a 160 gallon tank that's 96 x 24" x 16"h with acrylic. Cost of tank will be about $270.

If I build the same tank out of plywood/glass, the cost would be about $190. $60 for plywood, $80 for glass, $25 for drylok, $25 for screws/silicone/glue. Thats' not enough dollar savings to butter my thoughts about plywood tanks.

I can buid this acrylic tank in 1 day easily, the same can't be said about building a plywood/glass tank.
FeatherfinFan said:
Sorry to hear of your problems Keith, It's a shame how high Acrylic pricing is these days. Just a couple years ago I was getting 1/2" Plexiglass G (CellCast) for $138 and that included up to 4 cuts.
Be happy for me. I get to build another tank now. Being that the cost of acrylic is so high, a long/wide shallow tank with a big sump is probably the best solution. A 16" high tank suits my fish perfectly.
My plastics supplier is still getting me a quote for cutting the acrylic. There might be a 2 week lead time to get it cut. So I figured I can build the island, the stand, and fix the old 90g tank in the meantime.

Today, I got the materials I need for building the Cave Island Cove.
What I got-
Quickwall Cement-
Black Lava Rocks
3 Cans Great Stuff Foam
1 Can Waterfall Foam
Foam Sheets
10 ft 4" PVC Pipe
4 - 4" PVC Tee's

I've got lots of Malaysian driftwood that I might try to incorporate also.

I might start building the island Tommorow. It should be lots of fun.
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Looking forward to seeing this come together Keith, please take some pics along the way bro :)
FeatherfinFan said:
Looking forward to seeing this come together Keith, please take some pics along the way bro :)
Me too.

Your drawing seems cool, cant wait to see how its going to come together.
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