Backyard Aquaponics
A place to discuss aquaponics

Hi all,

trying to get an idea of what size pump to purchase.

What is your water turnover per hour?

ficticous example
supporting 100 silver perch from fingerling to 500gm
total 2000L of water in system (tank + growbeds+ sumps etc)
Approx 800L of water out of 2000L of growbed
Pump 1200lph at installed head height
1200 / 2000 = approx 60% of water turnover per hour through growbeds and
1200 / 800 = approx 1.5 Flood / drain cycles

Skygazer. from your figures you seem to be suggesting that 800ltrs of your system will be within your growbeds or sump at some point in time...

Leaving your tank with 1200ltrs..... or looking at it from another point of view, you appear to have slightly less capcity of growbed to tank ... a 1:1.5 ratio.... growbed to tank .... way off the optimum 2:1

Personally I think that the stocking densitiy might be a bit high to manage safely.... certainly as your fish approach 500gm size ... 100 of them in 1200ltrs will be producing a large amount of ammonia and solids wastes...

At the very least I think you will have to double your growbed capacity to cope in the future....

Regarding turnover, then yes I think in order to providse enough oxygenation to that many fish in 1200ltrs you'll need to turn over your system capacity at least that often.

Myself I think you'll be flat out managing your system with that many fish...

Anyone else think the same???

Your figures are a little confusing
e.g. Rope thinks you have only 800litres of GB as I read it as 800l of water then GB could be 2,000l

I have 2,500l of fish water and a 3,000lph pump (which is prolly pumping around 2,500lph)...this provides a nice turnover/hour and plenty of aeration. (I use continuous flow...others using timers differ)

My GB/water ratio is about 1:1 - just work on 6kg/100l for an experienced Aper

That is 6kg/100l of fish water or 3kg/100l of GB volume

Yep Elks right... interpreted 800ltr as the growbed volume ....

Still even at a 1:1 ratio as Elk says.... as an experienced APer....



So a 100 is OK, but pushing the limits unless experienced

Skygazer,we need pics. Do you have the capacity to add grow beds or vertical towers as your system matures? Nightingales down here have fantastic sump pumps for $89. If there is one up there, check them out. Buy a slightly bigger sump pump than you think you need, add a ball valve b/n it and ur fishtank to wind back ur return cycle time, increasing aeration. Then when your system matures and you add more gbs, you can open up your ball valve fully and use the existing pump.

You will get a feel for things as your fish grow, test regularly your water bits n pieces. The single most important thing imo is aeration, fish will forgive imperfect conditions if there is plenty of air. If as your fish are maturing you find your system unable to cope, you can eat 'em, offload them or whatever.

Have fun, don't break the bank and keep us in the loop.

Guys, i'd personally include the water in the growbed part of the system in the total water volume. The way i look at it, it is still part of the system as far as dilution of "levels".............................

you'd probably want a 1x per hour turn over at the very least.

I did

when I had my barra I only turned over the water about once every 2 hours and that was fine imho

Mine turns over once every 3 1/2 hrs but i have airstones

fair point guys.

My system turns over 5x/hour, but I'm overstocked and could use more growbeds. It was lower (3x/hour), but I had to raise it to keep good water quality. Too many tilapia

Mine goes a little less than once per hour.

Mine is about 10 times an hour.... Now thats over kill...

Sorry, I am still in the planning stages so no pics.

space wont really be a problem,but have not chosen exact location on property.

To add some more data to the system, as of last night I have landed myself a free upgrade to a 4700L tank instead of the original 2500L, so I can add more water to the system but due to costs my growbeds will be limited to 2000L for the first 12 months.

So proposed system is:
100 silver perch
4700L fish tank (round 2m diameter x 1.5M tall) - help me decide how much water to use.
2000L Grow bed = approx 1200L of 10mm gravel + 800L of water
At this stage grow beds will be above tank water level
water will be pumped from tank to GB.
Pump size ? - help me decide required water turnover.
Flood & drain with auto siphon from GB back to tank
Air pump stone in tanks to assist with DO - Air Pump

How deep is the grow-bed sg. This is relevant because you will need a decent surface area to grow the plants needed to pull the nitrates out of the system.