Backyard Aquaponics
A place to discuss aquaponics

Help up to the stage of buying pumps, phil at the pump shop wants to know what flow rate is req.. i have a 2500 litre fish tank and 4 bath tubs the 5th bath tub is the sump does any one know what i should look for in a pump ie flow rate
cheers rod

Also Phil will want to know if the pump is required to be continuous duty - which depends on whether you're using bell siphons or plain plumbed standpipes.
I was asking in another thread about GB volumes, according to the responses I got ~40% is taken up by the gravel - so work out 60% of GB volume and find a pump that can fill that volume in less than 15 minutes (doesn't hurt to get a higher capacity pump in case you get more Gbs later).
That should get you in the ball park - if not, there'll be plenty of people here to tell you otherwise.

Your problem will be trying to not pump the small sump dry - just get a 1000 - 2000l / hour pump.

UY i believe that the ratio is the other way around 60% gravel 40% water.

yep OBO. 40% max fill rate as water is a good general guide.
mizzie, you could reasonably have a max of 1250 litres out of ur fishtank imo during pumping, if you are stocking lowish fish levels. That leaves 1250 litres as a max amount in ur growbeds, the same as the lowest level in ur fishtank. Bathtubs are roughly 250 litres. 40% (max fill rate per bathtub) is 100 litres. You could comfortably run 10 bathtubs off ur 2500 litre fishtank and reasonably expect it to remain half full during pumping.(Let's assume the water in the pipes = the water being returned from the sump.)

On 15 on 45 off, I would want to move at least half my water per hour, (you need airstones too.) So, something that moves about a thousand litres in 15 minutes, ie 4000lts an hour, will do the job at 10 bathtubs with reasonable fish density. That is approx where I would be heading. ALWAYS buy something a bit bigger than u think u need. Invariably it will be a sump pump in ur next BIGGER system. There is always a bigger system on the drawing board!

Small pumps get blocked and don't last. Plenty of really reliable pumps for a couple hundred bucks or so, good investment.

One last thing, my bathtubs sit below my fishtank. To get a clean siphon break at the end of the pump cycle, you need a return line from ur pump back into the fishtank. This will create a bit of aeration. The primary thing tho is it will stop the water from siphoning from ur fishtank after the pump cycle. In the event ur sump pump died, u would drain ur fishtank. The return valve from ur fishtank line will cause a clean airbreak at the end of ur pump cycle and u won't have to worry about waking to an empty fishtank and dead fish. Another reason to buy a slightly larger pump as u will be returning some water to the tank, not sending all out to the grow beds.

Hope this helps, prolly clear as mud. Welcome and get stuck in. (Pics man!)

Yay - I was right for once