Backyard Aquaponics
A place to discuss aquaponics

Maybe a simple question but, nothing is simple..

my growbed is 4' x 8' by 10" deep, lined with pond liner and filled with hydroton. I have two bh fittings at the bottom at one end of the bed, one connected to a loop siphon and the other is an overflow. I am using plastic drain pipe to keep the hydroton from contacting the filters on the bh fittings.

I am trying to determine how big of a sump I have to have to supply water to the fish tank which will overflow into the grow bed, which will fill and then drain.

So, the question is, at about 22 cm in depth, how deep should the water fill to before I want the siphon to kick on? Or.. half way, most of the way?

cheers

peter

Most people flood to about 1" below the top of the gravel or other media. It is good to keep the top of the gravel dry or algae grows, stem rot can happen, and more water is lost to evaporation.

If you can figure out the total volume of your grow bed/s then make sure your sump will hold at least half or a little more than half that amount to allow for some depth for the pump and evaporation before running dry. As a rule of thumb (though it can vary depending on type of gravel and mass of plant roots) people usually figure that a 100 l tub filled with media can hold 40 l of water when flooded or 40%. I usually round that up to 50% just to give myself extra leeway and make the figuring even easier. More protection from sump overflow or running the pump dry. If you have enough extra depth you can easily install a float top up valve in said sump (above the pump running dry level but below the normal low water mark when all beds are flooded) so that as water evaporates from the system, the top up can keep you within the proper water level range.

I actually rather like the idea of having a sump tank as big as the fish tank for a continually running system with twice as much grow beds as fish tank or 2:1 ratio as they say.

Excellent, thanks

still having a bit of difficulty with the 2:1 ratio, so help me out here.

my fish tank is a 100 gal tank, and i suppose it will be filled to about 90 gal.

my grow bed is 4' x 8' x 9" with about 50% media filled so about 90 gal, but it is really about 180 gal of total volume, solids and pores (air and or water).

But to fill the the growbed with water i will need somewhere near 75 gal, thus that is my sump volume correct?

So I add another 75 gal of sump I would have about 180 gal of space in my gb and 165 gal in my water system.

not really close to a 2:1 ratio,

If ones adds more gb then one needs a larger sump to fill the growbeds or.... 2 pumps and a timer.

Should I just decrease the water volume in the fish tank, to say 50 gal?


cheers

peter



peter

woah

Hope this will make it a little simpler.

The ratio is about the total grow bed volume to the total fish tank volume. The ratio is about the amount of growbed (filtration) compared to fish living space.

Don't worry about the total amount of water in the system when figuring the ratio and don't worry about the % of water it takes to fill the growbed etc when figuring the Ratio of growbed to fish tank.

You only worry about the % of water to fill the grow beds when figuring out how much sump you need or how much the water will fluctuate in the fish tank of a simple system.

You only worry about the total amount of water contained in a system if you need to dose with salt or something like that.

If the total volume of your grow bed is 180 gallons and the total water in your fish tank is 90 gallons, then you have a 2:1 ratio.

If your total grow bed volume is 180 gallons I would tell you to make sure you have a 90-100 gallon sump tank just to be safe (that is my personal opinion about the needed capacity for the sump tank just to make life easier, allow depth for the pump to work, and perhaps let you install a float top up between the pump dry level and the normal low water mark.)

2 to 1 ratio is just a guide the main thing is how many fish and plants [ people run 20000 litre pool and 2000 grow beds successfully so start with what you have and go from there
I currently have 5000 fish tanks and2000 litre grow beds and its been running without problems for 2 years

I probably have 1500 gallons of grow bed and and 1000 gallons of fish tank on my big system and I think it is a pretty good balance so far.

okay, thanks


i will have it set up and running in a few weeks and will keep you posted

peter

OT: Every time I read the first part of the subject line the Bee Gees pop into my head.

I suggest an immediate term in "rehab" DD ...