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aquahealth
12-26-2012, 05:52 AM
I'm planning four grow beds, 4x8x12"deep, which should equal about 120 gallons of water each, after considering the displacement of the media, which equals 480 gallons for four grow beds, plus a 320 gallon fish tank, which equals 800 gallons total. My understanding from DIY is that a flood and drain four times an hour is good. So, is an 800 gph pump needed, or a 3200 gph pump needed?

I'm planning on only using the type of goldfish that only get around four inchs long, so with a 320 gallon fish tank, will that fish tank be able to support the four grow beds?

If I had a plant every six inches, that would equal 105 plants per bed, and 420 total. So, I need to figure out if ALL these numbers will work together in harmony.

Thanks much.

bsfman
12-26-2012, 06:53 AM
I'm planning four grow beds, 4x8x12"deep, which should equal about 120 gallons of water each, after considering the displacement of the media, which equals 480 gallons for four grow beds, plus a 320 gallon fish tank, which equals 800 gallons total. My understanding from DIY is that a flood and drain four times an hour is good. So, is an 800 gph pump needed, or a 3200 gph pump needed?



Are you planning to run flood and drain growbeds? If so, you will need to add a substantial sump. If you flood and drain directly into/out of your fish tank, the capacity of your growbeds with your proposed configuration exceeds the capacity of your fish tank. If all four GB's happen to cycle coincidently (and this will definitely happen at times) you will wind up either totally draining your FT or overflowing it.

You can probably figure for planning purposes about 40% of each fully flooded GB to be water - so about 96 gallons. Running one GB directly in/out of your FT would be 96/320 = a 30% fluctuation in water level in your FT. I wouldn't want to go any more than that. It would be too much of a water level fluctuation for happy fish.
If you add a sump to support all four GBs, it will have to be at LEAST a 400 gallon sump to accomodate simultaneous filling/draining of the growbeds.

On a positive note, you could get by with the smaller pump running a single GB. The downside is less growing area and biofiltration. You would have to adjust your fish stocking level accordingly.

Running all four GBs in a constant flood mode would eliminate your water level issues, but possibly restrict you on growing certain crops.

I've strayed from your pump question though. To cycle 4 GBs 4 times an hour, you are looking at a 1600gph pump at a minimum. Add a fudge factor for efficiency loss in pumping uphill, and you probably want something in the 2000 gph range. It's better to have more pump capacity than you need. You can always divert the surplus capacity for aeration/circulation in your FT.

aquahealth
12-26-2012, 08:56 AM
bsfman, yes, flood and drain. The fishtank will always keep the same level. There will be a stand pipe in it starting at the bottom and going up to a tee, so it can't syphon, and this pipe will be a good size, 3 inches, to handle any fast incoming water. The pipe will go to a 55 gal mechanical swirl filter, then to the bio filter, then to a sump, then to another sump with duckweed surrounded by foam, so the duckweed will float up and down as the water level goes up and down, and also so the duckweed will not stick to the sides of the tank, then to another sump, and this is where the pump will be, which will be connected to an an in-line bio filter, for more filtering and also so no duckweed can get into the growbeds, because that is where the water will go next. The beds will empty directly into the round fish tank, and will cause a swirl so the waste will go down and to the center of the six foot diameter, two foot high, round, fish tank, which will be where the stand pipe will be. There will be an extra line from the water pump, pumping water in an upwards direction in the bottom of the stand pipe, to help draw the waste even faster, and get the waste out of the fish tank very fast. I hope that works, but it seems to me that it can only work better. I can only think that the speed at which the waste is removed from the fish will be very helpful for overall performance.

I'm thinking now, since the fish tank level will always be the same level, perhaps I should not use that water when figuring out water flow and pump size, and instead, only the grow bed water. Does that make sense? But I do think your suggestion of a 2000 gph pump would be the right one. Thanks for your help.

Corey B
02-24-2013, 11:23 AM
I Think you may have lost every one. I know you lost me. Why so much filtration and sumps before the grow beds?

bsfman
02-24-2013, 01:20 PM
I Think you may have lost every one. I know you lost me. Why so much filtration and sumps before the grow beds?

It's probably a very wise idea to enable filtration and settlement of solids prior to the growbeds. Shoveling and washing the 12 tons or so of gravel he will have in his 4 growbeds to unclog it from fish turd accumulation is NOT a fun job! (Don't ask me how I know this!)

keith_r
02-25-2013, 06:53 AM
duckweed doesn't like "flowing" water, if you want duckweed, set up a smaller (i used a 30 gallon preformed yard pond) and just drained solids from the system into it occasionally, and the duckweed grew very well (with a couple minnows to keep mosquitos out)
regarding the pump... size it so that it will turn over the volume of your ft at least 1x hour while taking into account how much head you nead (height you are pumping the water) - oversize it a bit and add a T before the growbeds to put a little flow back into the ft and add aeration with your water pump

Lordshandyman
02-26-2013, 06:20 PM
What size drain pipe will you be using for your growbeds?

I suspect that drain size effects cycle times greatly. I currently have 3'x8'x1' growbeds with gravel median, and used 1 1/2' drain pipe. My cycles per hour were way too many, as my water volume had to be high to produce a syphon with such large pipe. Also, with such large pipe, it has a really strong syphon and drains really fast, starting the cycle even sooner. But, I am testing this theory this weekend.

bbikebbs
02-26-2013, 09:39 PM
What size drain pipe will you be using for your growbeds?

I suspect that drain size effects cycle times greatly. I currently have 3'x8'x1' growbeds with gravel median, and used 1 1/2' drain pipe. My cycles per hour were way too many, as my water volume had to be high to produce a syphon with such large pipe. Also, with such large pipe, it has a really strong syphon and drains really fast, starting the cycle even sooner. But, I am testing this theory this weekend.

I'm using the typical IBC tote cut in half with the grow bed (approx. 3'x4'x1') using gravel on top. My down tube is 2" with a reducer (2 to 1 1/4") on the outlet under the bed. My cycle time is about 10 minutes to fill and 1 minute to drain. Been working since last May with no issues so far.