Backyard Aquaponics
A place to discuss aquaponics

I have a Greenhouse that I am building and need help with an idea that I am trying to see if it will work.

I have a large fish tank that pumps fish nutrients to a bio-filter about 6 feet above it. I want the nutrients to flow down the bio-filter into a drain and then go to a T that I can use a ball valve, to divert it to 6 shelves or back to the fish tank.

When the nutrients go to the shelves I want to be able to have it start on one end of a shelf and flood that shelf, then after a while drain to the next lower shelf flodding it and continue down all 6 shelfs.

what would I use to do this? Would it be best to do a flood and drain set up or a siphon set up or is there something better?

Should these shelves be level or should I have them sloped down towards a drain?

Has this been done before and is there a topic anyone knows about?

Thanks in advance fo any help.

Hey JoeB:

What media is in the biofilter - is it a grow bed or is it going to get clogged with solid over time?

I am planning something a little similar, except I want to pump from the fish tank to a settling tub, with valves to pull the solids out from the bottom of the settling tub, to planters. If the valves are all off then the solids would continue to settle in the bottom, and the tub would overflow clean water out the top back to the tank. If all the valves are open to planters then it wouldn't be accumulating solids at all, probably.

Cascading to all the shelves at once would use the most water, this might not be a big deal if you have a big tank relative to the shelves. Another way is you could have a siphon on each shelf. This allows each one to be in a different part of the cycle, reducing the average drop in the fish tank to about 1/2 the volume you'd get if all were flooded at the same time. Rarely would all shelves be full at the same time.

Be careful to account for Murphy's Law in case one leaks or overflows. Situate the pump a foot or so above the bottom of the fish tank so that it can't pump the fish dry if the worst happens.

First of all I should explain what my fish tank is. It is a 4'x8'x5' deep tank below grade in my greenhouse made out of wood with a heavy duty plastic liner.

I have 2 bio-filters. The top bio-filter is a 4'x8'x4" trough. This bio-filter is going to be pea gravel on a slant with the drain on the low end. I will have watercress growing in it and also worms to help take out the solids. I was looking at Growing Powers set up for this. The nutrients from the bio-filter will go to a 2" drain pipe with T's in it with ball valves. The T's will be above my other Bio Filter that will be explained below. I am not sure how much solids will pass on to the lower Bio-filter.

I have another bio-filter I saw done in Hawaii below the top one. They used a 24" to 26" tank above their fish tank lined again with the liner. Then they had it filled with light weight lava rock and had a bell siphon in it. I want to make it with 2 sections and 2 bell siphons. They said it worked great and acted like a lung giving the sytem and fish a lot of air. One section will go directly back to the fish and the other section will be going out to my rafts.

Because the top bio-filter is about 7' off the ground I was hoping to run the drain from the T's, that are used for the lower bio-filter, directly to my shelf system. But I am having problems with this idea. I like your idea of using a siphon on each shelf so that I do not use too much water in the system, But would love to have this maybe done in another way. I had another thought just now and maybe I could make the remainder of the nutrients that come from my T's go to a holding tank on the ground and then use a timmer and smaller electric pump to do a flood and bell siphon set up to the first shelf and then it would drain to the second shelf on down the set up of 6 shelves with the last shelf empting to the fish tank.

The idea of the shelfs is for sprouting seeds and growing smaller baby greens and grass for livestock and just getting plants started for the raft system I have going. I do not think that it would need constant flooding but a timer should do it.

Whats your thoughts?

I had a friend suggest to make the shelfs with standpipes that would keep some nutrients in the bottom of the shelves so the roots from the trays could stay wet and keep the trays up off the bottom of the shelfs with a 1 inch riser. Then use a extension on the standpipe and flood the top shelf, leave it for a while and turn off the source manually. Then put an extension on the next shelf down and remove the extension above it allowing the top shelf to go back to its lower level and thus flooding the second shelf down. Continue down to the bottom shelf but all done manually.

The idea works but wondering if anyone that uses electric pumps with ebb & flow has any ideas on how to do this automatically with a timer?