Fish Tank/Grow Bed Ratio

[Bidadisndat]

Quick question here: On the basis of a 1:1 ratio, is it the volume of water only that is spoken about, or the physical volume of the grow beds, expressed in litres?
I'm trying to work out roughly how many bathtub growbeds could be supported by a 2000 litre fish tank. As a bath tub may contain 250 litres of water without any growing media in it, but will hold considerably less with the media in it, which volume should I be using?
......Bid...

[Castaway]

I don't think you need to be too prescriptive with volumes in these cases. Nature is pretty forgiving. Just stay close to the ratio more or less...Your plants will tell you if they are stressed and not getting enough nutrients. Thats my 2c worth.

[Bidadisndat]

If I have bath filled to the brim with water, and then enter and lie down in it, there'd be a considerable overflow which would be very evident when I got out. Now, I know that my body probably has more volume than the volume of clay balls needed to fill a tub, but it would still equate to quite a bit of water.
I would hope that mother nature is more forgiving about volumes than is Mrs Bid, who constantly reminds me that mine is increasing. :lol:

[suncoastaqua]

From my understanding, it's the volume of the grow bed that you need to look at, without taking the media/displacement into consideration.

[Murray]

The 1:1 ratio is based on volume. Total volume of the fish tank : total volume of the grow bed.
It is only a guide.
As Castaway says, the plants will soon tell you if there are not enough nutrients.
Most bath tubs take around 300 ltrs.
If you have 300 ltrs of clay pebbles in a 300 ltr container it will take around 120 ltrs of water to fill the grow bed...depending on the actual clay pebbles you have that may change.
Once your system is up and running well, and your fish have a bit of size on them, you can push that to 2 grow bed volume to 1 fish tank volume very easily, some members have gone further than that.

[Bidadisndat]

Thanks guys, that helps a lot. Presently we have 6 bathtubs set aside for an AP system, which initially appears would go well with the stock tank. I'm hoping that once I have a successful setup operating the Minister of Finance and War will approve the purchase of some 'real' grow beds.