Backyard Aquaponics
A place to discuss aquaponics

dirty pool already eh, a curse on ur bathtubs i say.

I need to get the VRC handicapper in to give me a fair crack, given worms has already jumped from the starters gates.

Im trying to figure out the optimum stocking rate with 3500ltr tank and 16bathtub gb's

c'mon TT, i thought you would of been straight on to it to the decimal point!

anyhow.....I have a bit of a puzzel at the moment, murky water, seem like an algae growth but the cause unknown. no direct sunlight, low bio-load good cycling, good aeration....any ideas??? Im running the pump all night to see if that makes a differance. One thing i thought it could be is water levels in the grow beds, it comes to just below the surface...not the 2-3cm i've read it should be

Another thing... Im planning on adding 200 odd fish in a month and bring 10 more bath tubs on line. I have read not to add the fish in one hit, whats the alernative when they rock up at once?

help...please...anyone.....

no feeding and close water quality monitoring / water changes for a few weeks.

What Steve suggested....and start practicing HSM

Maximum of 6kg of fish per 100l tank, when you have the optimum 200l of GB per 100l of tank. In this case, your GB volume is the limiting factor; no more than 6kg of fish per 200l of GB. Average bathtub is about 200l, so that makes 16x6=96kg of fish?

Wow, you could have 35 bathtubs hooked up to your tank..

No expert advice here, just speculating, probably is related to the high water levels in the GB's. Besides the advice already given I would add, see if lowering the levels in GB's has any effect.

Kevin

xzorby, great break down by the way,

but i have always wondered about the 2:1 ratio. let say, 100l fish tank, and 200l of grow bed, what i have always wondered, how do you flood 200l of grow bed with 100l of water, and still have enough water for the fish? i know gravel make up most of the difference, but in a F&D, would there be enough water left at mid cycle?

just a newbie askin newbie questions

-df

i forgot to add:

is there a way to find out an average gravel displacement, for pea gravel? like an engine, to calculate the difference.

and of course fish tank water levels are going to depend on the over all service area of the fish tank.

-df

DF,
Fill a container of known volume with gravel. Then pour in water. See how much water it takes. As an example, my 50gal growbeds take about 13gal to flood. It will depend on the gravel/media you use.

i am wondering if there a ruff equation to all of this( i guess i might need to make it )

Equation?? We don't need no equation!

It really will depend on the media you use. The finer the media, the less water it will take. I originally thought 40%-50% (so was expecting 20-25 gal to flood my 50gal growbed). Turns out my particular media mix (crushed coral, hydroton and 3/8" river gravel) is 25%. If I went with the 3/8" beach gravel, the % would have been lower still. The beach gravel I can get is a wider mix of sizes, so it should pack a little tighter.

My equation was very simple. I took a 5 gallon bucket and filled it with my media, then measured how much water I was able to put into it. In my case, I am running 1/4 pea gravel. I filled, pressed, shook, made sure it was not going to compress much more, I even filled and emptied a few times to give everything a chance to settle down. I put exactly 2 gallons of water in after that.

I know there will be some minor diffences with the larger system, so, I just designed in a wide margin for error. So far though, it seems to be quite accurate.

I don't think that is too precise to mess with Janet's "no equation" requirement.

Mathew

Also, don't forget that you could set up a sump and/or header tank to minimise the change of water level in the fish tank.

Dank Fish, I'm very much a newbie as well.

DF, as was subsequently mentioned, a 200l GB doesn't hold 200l of water after you have taken in the media (nominally around 40%)

I have 6 GBs of ~460litres each (~2,800l), my fish water totals ~2,500l...there is only 250 litres of water out of the fish tank (in the GBs) at any one time...only one GB is full or filling at any one time...so it is the way you set up the system so that there is e substantial amount of water available to the fish