Backyard Aquaponics
A place to discuss aquaponics

I think talking about flow rates is not a good measure. Like Fish Tanks it is more about replenishment and it is very highly related to system size and method. Small tubs versus channels etc. After all Kratky grew lettuce with 0 flow in his original experiment.
So you need to relate flow rate to the total volume being turned over - then these numbers would probably make more sense. (ie. DWC volumes per hour or something).

also DWC has three factors - nutrients, circulation and aeration (DO).
so if you have air bubblers that may change the dynamic than if you rely on water flow for aeration and they would also provide circulation. So again becomes an issue of replenishment / turn-over.

Das Boots (Andres) system is in caretaker mode so not looking for high growth - cant recall if he is running air or not.
Suspect he might be.

[edit] actually Andres does as captured in Sams quote - as usual DB is on the ball.... " It takes an hour and a half to turn over each DWC,so the pump comes on for 1 1/2 hrs in the morning the same early evening,air remains on 24 hours. "

Yes, back in early 2016 he said he was running 60 lpm of air in each DWC and I believe he used 1.2m placement like the UVI system, but I couldn't find a quote on that for sure...





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Sam

so we can conclude that Andres gets about 2 DWC volumes per 3 hours if he were to run 24/7 .
ie. under operation he is getting quite a few a day at least, plus he runs air. But doesn't need multiple per hour.

(current doesn't count as he is in caretaker mode, but presume the flow rate = turnover = 1.5 hours remains same even with system in operation. So even with 24/7 he gets a DWC turnover per 1.5 hours)

In context of BYAP and small tubs/drums like OP and Pete are talking about, probably most are getting multiple turnovers per hour, even without air and even on timer. So probably doesn't really affect much at all - Sams quoted studies favour slightly more rather than slightly less without getting carried away (eg. first one cited)..

However I think when someone says "we’ve gotten very good growth rates with flow rates as little as 2 gallons per minute, we’re now recommending 5 gpm " there has got to be a little stretch in suggesting it is conclusive. [maybe they sell pumps]. At end of day good growth is good growth for most BYAP'ers.... and a little extra turnover doesn't hurt