Backyard Aquaponics
A place to discuss aquaponics

How does one know if one has his grow bed water level to high or low in a constant flowing system

Not sure what you mean by "constant flowing system"

Constant flowing as in the pump is running continuous - or NFT/DWC

Flood and drain grow beds
the standard most of us use - set water level ~50mm (1") below the level of the grow bed media

NFT/DWC - you may need to supply more detail




welcome

I am using a flood drain meaning half barrels cut and filed with gravel,
So 1" below grow bed media.
I will check that today as i started yesterday
I am not trying NFT or DWC yet as i will be out of the countryfot bout 2-3 weeks
Also I should avoid any metals as i was going to put an iron mesh in bottom to keep a flow going
Thanks

Yep - this keeps the top level of the gravel dry and so no algae starts to flourish on the media...and provides a substantial amount of media for bacteria

Iron should be ok

Wait, if the water never touches the top 1 inch then how does the bacteria get to the water to convert the Ammonia?

The bacteria grows, lives and does its nitrification magic... in the thin film of water that surrounds the pieces of media (surface tension) and all the nooks and crannies in the media...

If you flood to the top of the growbed media... the sunlight causes the nutrient rich water to form an algael slime on the surface of the growbed... which ultimately starves the growbed of oxygen....

Keeping the flood level to about 20-25mm below the top of the media works just fine....

Does the bacteria drain back into the fish tank and do some work in there?

Bacteria will grow on every surface in the system providing there is food and O2.

Hence the need for the air pump? Whether the critters need it or not? Is that right?

O2 enters the water from the air/water interface ie FT surface, being pushed and pulled through the GB's, returned in a dump back into the FT.
There is some dispute over the need for air pumps, and I am not getting involved in it.

lol. Ok thanks. I am experimenting with Turtleponics and they don't need the airpump. So I was just checking to see if I needed one for any other reason.

No worries, I just get into enough trouble as it is

The bacteria doesn't move around too much, it tends to stay stuck to all surfaces that get wet and have enough aeration. Generally the grow beds for the plants are the place that most of the bacteria do their work since they are also light sensitive and would rather be on the media that is buried in the grow bed. Hence, you aren't loosing much by not wetting the surface of the gravel that is in the light.