Welcome..
marcelbohmer wrote:
..ill have a 1000L FT and 300L GB with 20 Goldfish, do you think I can add more Goldfish?
Depends - how big are your gold fish?
I have only two monster 400mm+ long "gold fish".. er, carp I mean, in one of my systems, eating about the same amount as my 50 smaller silver perch
marcelbohmer wrote:
Secondly, what size bell siphon do i need it my inlet pipe it a 20 mm pipe?
More important than the diameter of your inlet pipe is how much water turnover you will be pumping through the growbed? ie what sized pump are you using?
Even with just one growbed, common practice is to install one T-piece with two inline taps to feed the water in. The taps are used to fine tune the inflow water in order to make the autosiphon work. Any excess pressure is "T-eed off" back into the fish tank, using the second tap to control pressure. This way no excess backpressure is placed upon the pump - it is instead used constructively to add extra aeration to the fish tank
Regarding diameter pipe for autosiphon, this is what's most commonly used for a small setup like yours:
1) 25mm PVC standpipe
2) 65mm bell siphon
3) 100mm media guard
Number 2 goes over number 1, then number 3 over both of them.
Here's a photo of the above components:
Attachment:
auto-siphon kit.jpg [ 67.58 KiB | Viewed 2514 times ]
There are heaps of websites detailing construction of auto-siphons (some better than others), but let us know if you need more info