Dangling in water is not the same as full DWC... I mean I seen grows where roots grow down a return pipe and into the res but their top end is in the right conditions (i've seen that in NFT & Ebb n Flow) For you it looks like you are top feeding into a pot of expanded clay balls? Tons of air there to compensate for some of the roots being under water.
You didn't mention what type of fish they are?
About the deficiency, maybe you should hit them with a foliar spray right up until the buds start to get cluster
Once it starts getting actual bud though spraying will obviously be a mold risk. I don't know if you are trying to go organic or not but if you aren't adverse to chem you could maybe keep the foliar up to week 5 maybe if you had a good dose of h202 and colloidal silver in the spray to kill pathogens. You would need to know you have good ventilation though and no history of mold in the grow conditions.
that is exactly what it is. a 50l tub full of hydroton (clay balls) what you cant see is that there is actually a large colony of worms living in the hydroton. its crazy they seem to love it. the worms break down any solid waste that makes it to the grow beds and makes it available to the plant. as for the roots being in water it wouldnt matter because i have 2 large airstones running in the fish tank at all times, fish like air as much as plants and humans so i have as much air as i can in there.
next question was fish. i have probably 5-6 medium size comets/shubunkins in there so just regular old goldfish, i threw them in at about 3-4cm long and in a short time they have doubled there size. i also recently added 3 small bristlenose catfish to eat up some of the algae and add a little diversity to the mix. and for shits and giggles i got a cool little KOI for $5 which is all white with a big red spot on his head. any fish will do though and edible fish is an option.
foliar spray... i just dont like it ever. i used to use it in veg then stop when i hit flower but then one day my plants were all cranking along until i flipped to 12/12 and stopped hitting them with foliar, thats when i found out my nute mix had an imbalance and i hadnt noticed because the foliar spray was making up for it. trouble is the first couple fo weeks of bloom are crucial so yield was affected. now i wont use it because i like to know my plants are getting everything they need from the rootzone before i switch to flower. dont get me wrong they do work i just dont like them.
i wouldnt want h202 anywhere near my system. the whole thing relies on bacteria, the bacteria are the main source of mutrients in the system as they break down the fish waste and turn it into nitrates which the plants use. the worms are just a backup.
thanks for your interest it makes me feel like im moving in the right direction with this grow. oh and yeah i think im trying to keep it as organic as possible. i dont know how organic potassium sulphate (potash) is but its the only thing im adding so im still going to call it pretty well organic i should still get the added flavour boost that organic aquaponics gardeners claim to get so we will see.
