Displacing water volume in a tank?

[_Dude]

I'm considering modifying my modification of Blazeoneup's system (recirculating DWC using 5 gallon buckets) by putting each row of buckets into a homemade plywood tank. This would let me fill up each row with water without any plumbing to leak, and I could freely adjust the bucket spacing as needed.

3 buckets per row, with max 16" between buckets and another 14" of leeway make each tank 82" long, 14.5" high, and 13" wide. Filled to 7.5" depth that makes for 35 gallons of water in each tank, 3 tanks add up to 105 gallons of water, about 4 times as much as just 9 buckets and a controller.

I'd like to get that down as much as possible while increasing the weight (almost 900 lbs for 3 tanks) as little as possible. So, I'd rather not just throw bricks or rocks around the buckets to lower water consumption.

Any ideas?

I'd also like to hear from any handy/carpenter types about load bearing and what I can expect from this 2nd story floor.

Also, does anyone know if standard poly tarps are really 100% waterproof? How about standard pond liners? I need some kind of cheap, durable, flexible, 100% waterproof material to line these tanks since epoxy is way too expensive.

 

[_Dude]

Haha, I just had the genius idea of using WATER to displace water! Duh, I can just use water balloons or something like that.

 

[_Dude]

Come on, surely someone reading this knows if polyethylene is truly waterproof, or where I can get my hands on some cheap truly waterproof lining?

 

[Grat3fulh3ad]

waterbed matresses

 

[_Dude]

Hey thanks Grat, that's a good tip - at least for research into materials. After a quick search I see most mattresses are made of vinyl.

 

[raeky]

just keep in mind your 105 gallons of water will weigh at least 874.65 pounds + all the nutes and other gear you have there... I'd build the wood structure VERY strong to hold that.. and I wouldn't put it in my attic or anything.. ;-)

Plus why would you need buckets? Just build the channels of water, and a plywood or plastic top for the channel with holes for the net pots and directly hang into the water channels... then circulate the water through the channels with pumps...

My two cents.. ;-)

 

[raeky]

waterbed matresses

Pond liner would be easier to get.. and is much better suited for what you want to do.

 

[_Dude]

Pond liner would be easier to get.. and is much better suited for what you want to do.

But are pond liners 100% waterproof? It's safe to say that whatever material is used for waterbed matresses is 100% waterproof. I'm not going with waterbed matresses either, just saying...

just keep in mind your 105 gallons of water will weigh at least 874.65 pounds + all the nutes and other gear you have there... I'd build the wood structure VERY strong to hold that.. and I wouldn't put it in my attic or anything.. ;-)

It's going to distribute the weight evenly over a plane (tank bottom), so I'm not worried about the floor caving in. I'm not worried about the tank either, since I'll be going by DIY aquarium plans that are designed to hold about twice the water.

Plus why would you need buckets? Just build the channels of water, and a plywood or plastic top for the channel with holes for the net pots and directly hang into the water channels... then circulate the water through the channels with pumps...

For one thing I already have the buckets, for another if I need to I can isolate a plant by removing its bucket from the tank.

 

[Guest]

Hey thanks Grat, that's a good tip - at least for research into materials. After a quick search I see most mattresses are made of vinyl.

water bed mattress , pond liner both suitable the weight would not stress out a second story floor. If you have the time & $$ consider glueing and screwing the plywood then paint with marine grade 2 part epoxy paint, will give you a very strong water tight box with out the bunched corners a liner would give you. also a box that long will want to bow outward at the center. It will need some bracing across the top.

 

[Grat3fulh3ad]

water bed mattress , pond liner both suitable the weight would not stress out a second story floor. If you have the time & $$ consider glueing and screwing the plywood then paint with marine grade 2 part epoxy paint, will give you a very strong water tight box with out the bunched corners a liner would give you. also a box that long will want to bow outward at the center. It will need some bracing across the top.

Excellent Idea... An alternative to top bracing would be arched reinforcing ribs across the bottom every so often... Shallow in the center, thick in the corners and tapering into the sides near the top...

 

[_Dude]

I wouldn't be comfortable using anything but epoxy rated for potable water systems cracker, and that shit ain't cheap at all. I'd prefer to do it that way but not at first. Maybe later. Tarps and pond liners are cheap.