Backyard Aquaponics
A place to discuss aquaponics

With autosiphons it is often necessary to fine tune the amount of water going into the growbeds to get the siphons working just right. Valves are a handy way to do this. In a pinch I have used a rock and a hose clamp, but valves work sooo much better.

Have you found any reference on how big a pump you need? I'm getting a new tank next week and would like to know too. I had a Lowe's (It's like a B&Q) "200 GPH" pond pump last year and it was more than enough (possibly too much?) flow for a 55 gallon fish tank and three half-barrel growbeds. I ended up putting a T fitting on it and draining about half of the water back to the fish tank.

HTH,
Ellie

Yep, that is it!




You don't "have" to have a sump. You can pump from the fish tank to the growbeds and have it drain right back to the fish tank. The problem with this is if one of the hoses breaks then you will pump all of your water out and kill your fish.

The Solution is a "Constant Height In Fish Tank Pump In Sump Tank" system. (CHIFT PIST for short.) In a CHIFT PIST system you put the pump in the sump and have it push the water to the growbeds. The growbeds return the water to the fish tank, and the fish tank overflows out to the sump. Wherever you put the overflow in the tank is where the water level will stay, regardless of evaporation or mechanical failure.

-ellie

I'm curious as I was wanting to be sure before I build my first system, which would be better for my system? Constant-flow flood and drain, or constant-flow NFT? I am planning a system like gnash06's http://www.backyardaquaponics.com/forum/viewtopic.php?t=650 with a 6" diameter PVC grow bed-tube. I'm planning on 3 grow beds of 10 foot length containing 14.69 gallons/55.6 liters of gravel each (= 44 gallons/166.6 liters total). According to the "ratio" I have read about [1lbs fish>2 gallons water>4 gallons of grow bed], that should be good for 22 gallons/83 liters of water and 11 pounds/5 kilograms (end weight) in fish.

Is this correct, and if so which technique would you guys approve of using with my "proposed" system? I plan on raising Tilapia, and growing mostly your typical veggies in the grow tube (Tom's, cumbers, zuccs, squash, as well as a hop experiment).

With the original poster's question about valves and growbeds and sump and all.
With a 1:1 ratio system that is 150 gallons total of grow beds and 150 gallons of fish tank, you can probably get away with the simple system of pump in fish tank grow beds above the fish tank and draining back to the fish tank. That is basically what was done in Janet's Jungle. There will be some fluctuation in the level of the fish tank water and you will therefore not want to stock too heavily. The rule of thumb is that it usually takes about 40% of the total growbed volume to flood it. Going to a system with a sump tank has benefits but for a first simple system it is not mandatory.

As noted, having valves to regulate the flow in the grow beds will allow for fine tuning flow rate to get siphons working properly.

Pump size. If pump will run all the time, then you want to pump at least the volume of your fish tank each hour at the amount of head you are requiring of your pump. Most people will go a fair bit stronger on the pump to allow for expansion and extra aeration. Be ware that a pump that is called a 300 gallon per hour pump and has a max head height of say 10 feet, will likely not pump any water at just over 10 feet. Look for a chart that tell you how much the pump will supply at the height you are plannning for the top of your grow beds, be sure that number is more than the total volume of your fish tank.

NFT vs. Flood and Drain is one of those questions without a hard answer.. Sort of like "which is better, metal or asphalt roofing?"

The advantages to NFT are
- No finicky siphons.
- Lots of oxygen at the roots.

The disadvantages of NFT are
- "dead" spots where water channels away from roots and the roots rot.
- Aquaponics specific: Fish waste can settle in the NFT and decompose.
- NFT+gravel specific: At least one APer had to cut up their NFT pipe because the roots locked the gravel into big clumps.
- If not using gravel there is little surface area for nitrification, and an auxilliary biofilter may be required.
- Plants die quickly if a pump fails.

The advantages of Flood and Drain are
- Lots of surface area for biological activity.
- Worms!
- Easy to plant, no rockwool required.
- Cool factor of watching siphons kick off. (After almost a year, these things still amaze me.)

The disadvantages of Flood and Drain are
- Cost, depending on media. (Hydroton is expensive... but gravel is cheap)
- Siphons or timers, pick your poison.
- Mobility. I can move a full NFT tray, but not a 4x8 growbed.
- It is a PITA to clean out.
- Washing Gravel. (Rite of passage or not, this job sucks.)

Last thing, some plants do better in one system vs. another. I had Corn and sunflowers* side-by-side in DWC and Flood/drain systems last year. They grew remarkably better in the Flood/drain system.

* - It's probably best NOT to put these in a waist-high growbed. I needed a ladder to reach the corn.

I think I'm going to go with a larger pump like maybe 1000 gph or 1200ish. I'm just going to build a valve system to recirculate water back to the fish tank and slow down how much is put into the grow beds. Hopefully it works. Might help with the recirculation and aeration while allowing me to add more grow beds later.

As far as the sump.. still trying to decide about that. But I'll have to figure out my GB set up first anyway.. and the siphoning.. I'll set it up so that I can add it later if needed.

Just "tee" off the pump supply line Brandon ... with a return line to the fish tank... add a ball valve .. so that you can either close off the flow when you add more growbeds... or close off the growbed supply (if you ever need to do so)... and open the valve back to the fish tank...

Normally you would overflow from the FT to the sump and pump from the sump to the gb's. CHIFT PIST. Only problem if you pump from the ft is if you get a pipe failure/blockage you can pump your ft out.

I think I'm going to have to do it this way because I don't want the higher than needed powered pump to disturb the fish. I imagine it could cause problems in the confined space..

How big of a sump tank do I need? And as far as over flowing the tank would the hole be at the top of the water line and just have pvc connected and run all the way towards the bottom of the tank? Since I'm going to do continuous pump I need to make sure the water from the fish tank is constantly flowing as well.

as for the overflow I found this forum http://backyardaquaponics.com/forum/viewtopic.php?f=1&t=5302&hilit=SLO Somone mentions a box and another person mentions a venturi drain.

Either one work ok?

I would want to overflow from the FT to the grow beds (just to let the grow beds clean the water before it has to go through the pump) then the grow bed drain to the sump, however that is just me, I hate trying to clean up the solids and my current big system is having solids issues.

You want a sump tank big enough to hold all the water needed to flood all your grow beds at once and still have some excess water in it to keep your pump from burning up and perhaps enough extra depth to add in an automatic top up float valve. I usually try to go for a sump tank that is between the size of the fish tank and 60% of the total volume of the grow beds.

The plumbing for the fish tank, the hole can be anywhere from the bottom of the tank all the way up to the desired water line. Keep in mind that while water is flowing, the water line might rise a bit so don't go putting the plumbing at the very top edge of the tank. Make sure that there is a T at the desired water height because an elbow could cause a siphon.

You also need to make sure the plumbing is plenty large enough since gravity drains never move water as fast as water being pumped through the same size pipe and a siphon will also move water faster than a simple gravity drain through that same size pipe.