Backyard Aquaponics
A place to discuss aquaponics

Hi everyone

this is the 2nd build of my system which is an 800L fish tank with two 180L grow beds that are 110 diameter & 20cm tall. I started out by having 2 pumps, one in the sump and one in the FT but i was having issues with the sump pump being unreliable and my FT kept getting pumped out...ive probably wasted over 3000L of rainwater...oh well.

so ive changed my system to CHIFT PIST but its not working as expected. Im seeming to have issues with not enough flow out of the venturi drain and when the pump is on, my FT is filling up over the overflow T. im using 25mm pipe for the venturi drain and have drilled a few large holes down near the bottom of the pipe near the base of the FT. the connection out of my FT is 25mm. Is CHIFT PIST reliant on low flow? Is there a way to increase the flow out of a venturi drain other than increasing the pipe diameter?

I have a tap after my sump pump so i can wind it back to reduce the flow but when i did, i was not getting enough flow to fill my grow beds because they were draining faster than filling. I am currently using a standard stand pipe with outer pipe for the grow beds draining ala Joel at BYAP. I had two holes in the stand pipe but i blocked one up to reduce the drainage so the grow beds will fill, now my grow beds are taking about 45 mins to drain. ive read that this might not be good and plant roots might rot..should i worry about this? i have the pump on for 15 mins every hour so basically as soon as it completely drains the pump starts again.

Im wondering about using a bell or auto siphon to get faster drainage but i already have outer pipes buried in my grow bed that have many holes drilled in them (ala Joel BYAP) so im not sure if i can use them with the siphons or if im going to have to dig up my hydroton and plants....hopefully not.

im also thinking that im not getting as much aeration as i used to with the 2 pumps and im thinking of putting a spray bar in the sump tank to utilise the excess flow from the pump. would this be enough? I just have gold fish at the moment until i can get a stable system. system is only about 2 weeks old.

will this system work well as it is or do i need to change it?....any advice would be appreciated for a newbie. cheers.

Check out my system it use es 90 mm to the drop down then 50 mm i think your pipe is to small theres others running up to 15 beds with 90 mm

This shouldn't be a problem Clay... but I'm a bit confused as to why two relatively small volume and small depth growbeds would take 45 mins to drain...

What diameters are your standpipe and outer pipe??

And from the pictures ... there appears to be another pipe possibly connected (?) to the central overflow pipe in the fish tank... what is this?

thanks for the responses

stand pipe is 25mm, outer pipe is 90mm. i think the slow drain is because i blocked up one hole in the stand pipe so there is only one small hole to drain the grow bed.

the pipe on the top of the overflow T is put there because i have azolla in the FT and as the FT was overflowing quite quickly, azolla was going down into my grow beds.

with the venturi drain flow, does this mean that the outlet from my tank (25mm) is too small? thats going to be hard to fix. i might have to cope with low flow

That sure looks like 40mm pipe your using?

If not - bite the bullet and increase you pipework sizing - your looking at $100 max worth of fittings. Save a sheetload of hassle.

+1

the actual drain is 40mm DWV pipe. standpipe is 25mm. pipe work to grow beds is 25mm, venturi drain pipe is 25mm, and sump pump pipe is 25mm.

Yeah, change the tank standpipe.

yeah i can see now, too much 25mm!

how much would i need to change? would i need to just change the venturi drain to 40mm, the tank connector to 40mm? or the piping to the grow beds to 40mm or all of the above?

when you say 'tank standpipe' do you mean in the grow bed or the venturi drain (if thats what its called)? im still trying to get my head around all the terms.

The vertical pipe in the fish tank, they are also calling a standpipe, the venturi drain needs to be bigger. You will save yourself a bunch of trouble if you can manage to get another hole or increase the size of the hole in your fish tank to take a 40 or 50 mm pipe fitting. You want the larger size at least until where the flow splits to go to the grow beds.

Agree with TCL ...

yes i understand. i didnt realise that there would be a difference in flow between what was going in and what was going out if it was the same pipe diameter. i think i need to learn about water physics...pressure...etc.

thanks for all your help, now back to 3rd rebuild

Lesson 1: My most hardlearnt lesson.

Gravity will always win, but she'll win no awards for speed.
If you have gravity powered flow in your system, it usually means using a pipe 2-3 times as wide as what you'd need if you were using a pump.
Gravity can be temporarily bested with the use of air-locks. Good airlocks come in the shape of siphons. Bad airlocks cause overflows and much angst.

Nice looking setup there Clayton, Hydroton and all, they must pay you too much Have you sorted out the issues yet?

Growth looks pretty good sa far, do you get any wilting or drying out problems with the single inlet onto the hydroton rather than running a ring with holes in it that disperses the water around the base of the plants? Good if you dont as it is certainley cheaper and easier than making an octagonal rings like I did or using manifolds.

Keep learning, there is a rather large system awaiting setup at school when the term commences