Plywood tank questions

[Burton]

I have been scowering the net looking for a good written out plan on the wood needed to build a 300 - 600 gallon tank and have been unsuccessful.

 

I have seen koi ponds with no details to the wood thickness and necessary spacing of 2x6 ribs used, and I have seen aquarium builders using 3/4" plywood only with epoxy and glass.

 

Does anyone have any information so I can start to plan out the cost for the wood / fasteners / misc ?

 

Also in regards to EPDM pond liner, aka fish safe pond liner, I just read over at friendly aquaponics NOT to use this in your system ... what are the other options outside aquarium safe epoxy / fiberglass? Is there another "safe" pond liner I can use or am I missing some information?

 

 

Side note: Right now I am comparing costs of different tanks and beds as well as making a 1:1 scale of each option on my photoshop layout of my condo to see where the items will fit best. It seems IBC and making my own tank would cost about the same or close enough where making my own tank / beds would benefit me more given the space I have.

 

Thanks for your help

[Burton]

Found what I was looking for I guess, as far as the EPDM was concerned. But it seems it is pretty hard to find LDPE at the sizes I need. Also they are using plastic tanks and only using this as their raft liner, I wonder how it would handle against fish, might have to increase to 40mil to be safe. :)

Trough liner is ofter referred to as greenhouse cover material. It is 20 to 23 mils thick, is often reinforced with fibers, and is made from LDPE (Low Density PolyEthylene), and is usually found at the same greenhouse and nursery supply stores you can get the net pots at. DO NOT ask for hydroponic trough liner, NO ONE will have any idea what you're talking about. Two kinds of liner we've used successfully are 23-mil P2000 by Inland Plastics Company, and 20-mil DuraSkrim R20WW by Raven Industries.

quoted from friendlyaquaponics

[Burton]

At last something to read on the liners / plastics just had to change the search around some. http://aquaponicscommunity.com/forum/topics/liner-leaching

[TCLynx]

You can use epdm provided you get the fish safe pond liner (avoid the roofing liner)  Look for Firestone pondguard pond liner.  I've used tons of it and it is fine.  Just rinse it before filling for fish.

 

I don't really advise using wood though as I've had issues with termites not realizing where the wood ended and where the liner began and then I wind up with leaks.

[Burton]

The system will be completely indoors, in a condo :), so I am not too worried about termites because if they are in the house then I am screwed anyway, not to mention my neighbors as well. Thankfully my brother is in pest control and I can get it taken care of for free.

 

I am still looking into using a prefab tanks as well, many sizes, as it would initially be easier to set up. But the plywood tanks offer me the chance to better use the space I am limited too. :)

 

[TCLynx]

beware the possible leak issues if building a plywood tank for indoors.

 

[Burton]

The plan was to make the tank then put insulation foam inside first, seal this water tight, then put the liner.

 

Question for ya, since you are here, where is the pump in your 300 gallon system? You mentioned modifying the indexing valve to work with a gravity flow and I started to think how this might be laid out.

 

My thoughts were the FT is the lowest point in the system, this feeds water up to another holding tank which has a bell siphon connected to the indexing valve connected to the BG's higher than the FT. But I dont know how the indexing valve would react to the small flow of water before the siphon, would it cause a early siphon, would it not function at all etc.

 

TCLynx said:

beware the possible leak issues if building a plywood tank for indoors.

 

[TCLynx]

My pump is in the fish tank for the 300 gallon system.  It pumps directly to the indexing valve.  The reason it is a gravity modified valve is because the pump is a rather small one.  Normal indexing valves require more flow and pressure to operate the valve.  Please talk to me when figuring out what kind of indexing valve to use with what kind of pump and at what heights since it is all kinda important to get the flows and pressures right for it to work well.  I would recommend simply having the pump feed the valve since setting up a header tank will only require you to have a stronger pump to lift higher and the indexing valve will mess with siphon operation.  I've gotten an indexing valve to work with a barrel ponics type flush tank but then you have to maintain all that mechanism as well and you are still having to pump up higher.

I am going to be testing a FLOUT with some indexing valves here shortly but I haven't gotten the chance to work on it yet.

[Burton]

Currently I only have two pumps in my possession from previous projects. A pondmaster 960 and Hailea HX-6550, no really low power pumps.

It would be nice to pump water up to the second story of my house, doesn't help to have 9ft ceilings, so I can use space on both floors. Most of my natural light is on the second floor, either way I would still have to use extra lights. >./p>

 

The FLOUT looks interesting, especially the sequencer, but its seems like it would be more stuff to have to maintain and adjust ...  Couldn't you just attach a float to a flap valve instead? Granted even the flap valve can wear out.

[Chi Ma]

Remember the weight of the system. Water weighs about 8lbs a gallon. Make sure your floors can handle the weight.

[Burton]

Oh I know, you should see the google spreadsheet I have going, 1gal = 8.35lbs.

It also calculates the weight of the water given the sqft I enter for the GB's, and another column with weight of the GB media + water (sqft/2 in gallons*8.35) etc ...

Oh and they are auto calculations so all I have to do is change the sqft I desire and they will update ^_^

 

At 26sq ft a hydroton + water BG is about 1700 lbs, now I dont know the weight of my container yet but 1700lb spread out is about the same weight of a waterbed.

Lavarock in place of hydroton would be 1900 lbs at 26sq ft, river rock 3400lbs >.< but cheapest option, second cheapest is lavarock, and most expensive is hydroton of course.

 

I posted pictures of my condo layout and highlighted areas I can use for the system if your curious to see what I am dealing with ...

 

Thanks for your concern though, I have actually tried googling "water-bed through ceiling" as well as "fish tank through ceiling" and no pictures came up, but a very very long winded detail forum post did come up explaining it in structural engineering terms. I read it all 0_0

Chi Ma said:

Remember the weight of the system. Water weighs about 8lbs a gallon. Make sure your floors can handle the weight.

[TCLynx]

I might recommend two separate systems since pumping up an extra 10 feet to the 2nd floor is going to cost you a lot in energy consumption on the pump.  For most indexing valves you need some where between 10 and 25 gallons per minute (depending on valve) at 10 pounds of pressure at the valve, so that means your pump would have to deliver the gallons per minute at probably 15 feet of head and still have the capacity to pump quite a bit higher than that to provide the pressure.

 

If your electricity is really cheap there and you don't mind paying several hundred dollars for a high head pump then this might be ok, however do you really want to be running a 1+ Hp pump in your house?

 

If you go the flout tank method, then you still need a fairly powerful pump to lift water up to a header tank above your grow beds on the second floor.  But in this situation the header tank may take up space and block light and require regular checking and your circulation will be intermittent for the whole system (I like to move about twice the volume of my fish tank per hour minimum though I know some people manage only moving the volume of their fish tank once per hour.)  The header tank will have to re-fill between "flushes" which means more time between flooding each grow bed.

 

Ah well all conciderations to take into account.

 

Do keep in mind that an aquaponics system indoors is also going to up the humidity inside.  Plan to be running a dehumidifier if you are not living in the desert.

[Rick Op]

Burton Rosenberger said:

The FLOUT looks interesting, especially the sequencer, but its seems like it would be more stuff to have to maintain and adjust ...  Couldn't you just attach a float to a flap valve instead? Granted even the flap valve can wear out.

Hi Burton! The following have not been tested by me... I have been playing with the following setups conceptually and will definitely be implementing some form of FLOUT & Indexing Valve(s) as I expand. Why not infect your brain with this affliction and share the fun?

Header tank with FLOUT installed to feed an indexing valve. Can be a really small pump supplying this header but the bottom of the header tank needs to be above the growbed surface plus ~30cm. Small amount of complexity and failure points.

Pump to indexing valve. FLOUT Chamber as a master drain siphon for all growbeds. Same water level for each. Requires check valve on each GB so they don't all fill up at once. Need timer on the pump that provides the right amount of water. Check valve can be a problem point and/or expense.

FLOUT master drain, check valves on GBs, but instead of a timer stopping the pump, the FLOUT does so via a water sensor in the FloatyBox or a magnetic sensor. My current favorite plan. Requires voltage to a reed switch under the FLOUT's landing zone, and NC relay(s) on the pump's power supply.

Pump to indexing valve, with a "relief valve" before the indexer. This relief valve receives a signal when the FLOUT master drain drains a GB. Reduces the pressure seen by the index valve enough to forward the sequence. Cause of much controversy on Aquaponic forums.

Fish Tank above GB, FLOUT mounted to a side drain, feeding an indexing valve. FT level will fluctuate by the amount of water sent to the GB. Need to constrain the FLOUT at top and bottom of its travel. Need sump below GB level but the pump in sump can be small as there is no minimum flow needed to actuate a FLOUT.

There are other variations, which is why I have the "absent-minded professor" look most of the time...

Rick