Backyard Aquaponics
A place to discuss aquaponics

Can anyone give some info regarding the advantages and disadvantages of having a constant water level in the growbeds?

You mean like constantly flooded beds?

Well, first let me say it can work, Creative 1 does it in his system. You might read his system thread to see how things go there. Many others have had problems when they have done it but perhaps they didn't have enough aeration.

Pro-
Constantly flooded beads mean you don't get water fluctuations in the fish tank or sump tank.
Possible temperature benefit, as in slightly more stable temperatures.

Con-
Reduced aeration, possible need for more additional aeration to be added.
Constantly wet roots can lead to root rot if the water is not aerated enough
reduced aeration of the bio-filter can reduce it's effectiveness or cause high nitrite levels and even convert nitrate back to nitrite. (search for the oldest entries of "RSG filter" in the forum for an explanation of why.) Nitrite is very bad for fish so if you run a system that is going to have constant nitrite levels, you may need to figure out ways to outgas the nitrite to nitrogen gas which will add to the complexity of the system. This situation could also result in reduced nitrate levels for the plants but it is all a balance and you don't necessarily need huge amounts of nitrate for the plants to do well, you just need enough that the do, do well.

Thanks I will check out the system
and thanks for the quick reply

Well said TCL