Backyard Aquaponics
A place to discuss aquaponics

What is the ultimate flow from input to output of the bed?

do you mean the grow bed ratio? it's not a hard figure, 2:1 is optimal with higher stocking density, but for say 1 small fish per 20L you could get away with a 1:1 ratio with mature plants in the system

No the flow rate

Think I know where you're at Hunter....

Most people are trying to turn over the equivalent of their tanks capacity about once an hour ... at least....

This is done primarily for reasons of oxygenation..... this may be increased or decreased for the same reason, species of fish, seasonal temperatures, climatic location etc...

Obviously it is tied into other factors like the stocking density of your system and the ratio of filtration capacity to tank capacity as well...

ie. turning your water over two or three times an hour might provide aeration, but wont help filtration of your system if you have a thousand fish in a 3000ltr tank and only 6 half blue barrels (300ltr).....

Is that what you're after???

nearly there
like I could slow rate down to 1lpm or 40lpm
there is a big difference.
What would happen to the plants with a faster rate
e.g drown?

if they were continually wet at that rate they would struggle, but if you hit them with 40lpm, then give them 50 minutes off they would be fine.

I would go for the higher flow with a shorter run time to use less power.

great now you are talking
I have a 1inch down to a garden hose so I should remove hose and drill more holes in the outlet pipe?

garden hose runs on top of the media? If so, bigger holes = less disturbance of the media = more flow = shorter run time.

It all depends on you temps and humidity i guess, I have to run my pump for 6 hours straight over the middle of the day, because it get too dry even with 15 minutes off.

In short you want to wet everything, but not wash it away.

You're getting there Hunter.... yep in the end it all comes down to a balancing act..... how fast you pump compared to how fast you drain....

How fast you drain might depend on how you drain.... how fast you flood (pump) might depend how you flood/pump .... ie if you're running continously or using timers..... bell siphons, sumps with float valves etc...

I can dig the hose into the end of the bath as I have read it is not good to have the top 1inch of gravel wet.

In your case it looks like you will be draining/returning by gravity.... using a siphon could result in a faster drain.... hence a more frequent flood.

Just how do you drain the bath tub at the moment?

still confused
you said if they were continually wet at that rate they would struggle,then you say you pump for 6 hours?

Outback is also continually draining and likely to suffer extremely high losses due to evaporation in Kalgoolie

it drains from a 100mm pipe with holes in it over the drain hole

so faster better?
doesnt everything get washed away?