Backyard Aquaponics
A place to discuss aquaponics

ive just done my first siphon test of a new system (without grow media) and it took 50 mins to flood and 8 mins to drain. is this ok or do i need to invest in a bigger pump or what? i realise once its full of media the fill time will be reduced but it seem a hell of a long time to be filling. any advice please guys, andy

Ah yeah.... would seem a very long time.... even timed flood & drain typically works on a 15 min flood/fill....

What are the sizes of your grow beds.... and your pump??

its a 285ltr growbed over a 738ltr tank. had to build from what i had hence the odd sizes. to be fair the pump isnt very big. its only 8.5 watt not sure of the ltrs per hour as ive thrown the box ect. i was thinking if i get one thats 130ltrs per hour this should give me the 15min fill time that most people recomend?

From experience, if you're going to run a 285L GB as siphoned F&D then IMO you will need at least a 1200Lph pump (normally around 35-40w). That's just for the one GB, if you plan on expanding with another GB to better match your gravel:water ratio then you will need an even bigger pump, as you also would if you ran timed F&D.

I've been experimenting and playing around with pump and siphon sizes on two systems lately that both have 300L GB's, both 300mm deep, just different dimensions... and I can tell you, depending on head loss, plumbing design etc, a 1200Lph pump and 20mm dia standpipe in the siphon should give you around three and a bit F&D cycles per hour, roughly 14-16 mins fill time and and 4-6 minutes drain time.

A 25mm standpipe will give you 4 and bit F&D cycles per hour but is getting close to the maximum performance of the 1200Lph pump (I always like a bit of spare flow/pressure left over for flow adjustment).

as it happens i was just looking at a 1200lph pump on ebay thinking this would do the trick. i am intending to add another growbed the same size once this ones up and running and was going to get a seperate pump for this one anyway. i was figuring i can always keep the little pump i already have if i wanted to add a little extra flow to the existing bed. i was toying with the idea of adding upright 4" pvc pipes at one edge, filled with grow medium for strawberries, simply sitting on the growbed floor. i was assuming they would just have a constant flow of water without actually effecting the flood and drain in the bed itself. thus increasing my grow area. have you had any experience if doing this mr damage?

sorry in my first reply it was a typo lol was supposed to read id need a 1300lph pump oops lol

Remember - IMO:
cons - two pumps two points of failure.Try to incorporate redundancy if you plan to run two pumps.
Pros- two pumps sizes to handle both beds = redundancy

Keep your power requirements in mind.

Jtk07

Sorry Chipper,

I have no experience with strawberry towers, in aquaponics at least. Keep in mind though, the taller the strawberry towers, the larger the head pressure when getting water to the top of them... so the bigger the pump you will require. Even if your towers were only say 1m taller than the GB... you'd probably need to at least double the size of your pump.

That seems a bit slow to me... what diameter tubing are you connecting the pump to the growbed with?

My 30 watt 1900 lph pump fills my 300 litre growbed in 3 minutes! I'm using 19 mm diameter tubing all the way from the pump to the growbed.

It is slow, but with the media in the grow bed you would think the time would be less than half the "no media" fill. That would make it a reasonable fill time IMO.

I think hold out until the GB has media in it....

There is a big difference between a 1900Lph pump and a 1200Lph pump...

...but in saying that, the 1200Lph pumps I use could fill a 300L GB in much less than 14-16 mins, but the flow is regulated by the diameter of the standpipe in the siphon... if I try filling it any quicker the siphon doesn't break.

+1

I'd expect that with media you'll have a cycle time of around 20 minutes.

Ah that makes sense. I didn't realise you had extra pump capacity but chose not to use it

Yep... always best to have a bit of horsepower up your sleeve

I have similar system size to you,

i use a 3000lph pump, my tank is constant flood though (however the power switches off to let it drain for 15-30min every hour). I dont use a syphon.

WHilst its pumping a lot of water i think its good because it keeps the tank water aerated whilst its flowing.