Backyard Aquaponics
A place to discuss aquaponics

Filter - the shallow container is the issue here and maybe exacerbated because the media may have fines and/or soil. All this limits effective filtration and aeration. If done properly AP grow beds will provide more than adequate filtration in a simple small system up to IBC size.

Miracle Gro & fertilisers generally - yep it is all about knowing exactly what you are adding and what you a deficient in. So the usual 'seasol' recommendation (I think it is maxicrop in USA) basically provides additives and some potassium without any nitrogen/phosphorous. So if you have nitrate issues you avoid anything that adds more nitrogen.

moral - its all about **reading the label** of whatever you are adding and knowing what the consequences are likely to be to system chemistry.