Backyard Aquaponics
A place to discuss aquaponics

I've finally gotten to running the pumps (of course it was so one of the growbeds was full of water and not able to become a missile )
We have a wide variety of growbeds:
towers - trickling slowly
blue drum halves - flat and vertical - need to fill very slowly to keep pace with others, fast drain through loop siphon
medium bed (2000L) and big bed (3500L) - take a long time to fill (maybe 20 minutes) and even longer to drain (2? hours)

This very long drain time will lead to long changeovers in the flood/drain cycle.

How long is too long between cycles?

would it not depend of DO leves... I would have thought that water in the growbed with minimal movement would result in root rot ?

Add aeration to your fish tank when the fish get bigger Jaymie. At this stage, with so much water and so little fish, DO shouldn't be a problem I wouln't have thought.

Mine take 19 minutes to fill. Hurts the hip pocket on the power bill, but I can't see any way around it wituout buying a more powerful pump.

hmmm, now we are in an area where I need more info..
If you have a small pump running for longer periods, and you have a powerful pump running for shorter periods - does one use more $$$ than the other, or does it balance out?

We've already got Murray's big blue pump

Should I increase the size of the drain holes in the medium and big beds standpipes?

Yeah, or drill an extra hgole and see how it affects the cycle. Then reassess.

that's what I thought. Tomorrow, hopefully when there is no rain

remember J as you have it drain faster, it will also take longer to fill

yeah I know, more fun trying to get all the taps doing just the right thing

Jaymie, just trying to get a handle on your system...

Are you running the towers (constant trickle) to fill the blue barrels and splitting the "same" pump cycle to fill both the medium bed (2000L) and big bed (3500L)....?

AM, theoretically you are moving the same amount of water, therefore it uses the same amount of energy (in this case electricity). Probably uses slightly more for a bigger pump though, more friction in the pipes, pump has to work harder. Would be close though I think.

Nova

THanks there Nova, I thought that might be the case but I have been wrong before (way too many times), so I ask instead

The answer is: the work is the same either way, _but_ you have factors to deal with in losses due to size, friction, flow, etc. Higher flow rate would provide more friction through the pipes, larger pump may be more efficient, etc.
Short answer is, you probably won't notice at this scale, unless you have to run one pump significantly longer in your cycle to fill the same tanks

For example, if you have a timer with 15-min cycles, and it takes 18 min to fill, then you have 12 min of overflow (multiplied by your flow rate), versus if you have a pump that fills it in 12 min, you only have 3 min of overflow (multiplied by your larger flowrate). The water you move in that 3 min, will be more than you with the smaller pump, but the overall energy is based on how much water you move.

J, i assume that all the beds / towers are draining back into the tank in their own right?

If so then you will always have some water returning and giving you DO.

I don't reckon that the 2 hour drain cycle in the growbeds would be that much of a problem personally. don't forget the roots aren't going to be sitting in water for two ours straight, more and more of them are going to be exposed to O2 as it drains.

Why not leave it as is, and modify as required? Its always good to have another person operating on completely differing parameters

squueeeeek sqqueeeeeeekkkk!
I'll be the guinea pig then?

The towers sit above the blue drums and drain straight into them. All the beds of whatever size, drain into the sump which has a float and pump to refill the monster.

Rupert, the pump cycle fills all the beds at them same time. It is taking some work to get all the taps at JUST the right position so this can work.