Backyard Aquaponics
A place to discuss aquaponics

try a foliar spray mon...check the box for conentration...

On what i use 10 measures seems about right[my box has a measure in it]

I think the flow is around 2000L/h through the 6 nft channels, so around 300L/channel/hour

All the plants in the channels look pretty simmilar...

yeah, certainly no difference in plant between the start and the end of the channels.

The normal rate for nft is at around 1- 2 lpm..maybe the plants aren`t quick enough
Excessive light can cause bleaching of the leaves too.

yes hex, but aren't tradition NFT run to waste, hence the very slow flow rate?

These days Steve most hydro isn't run to waste in the sense that it once was.

Older hydro setups used gravel, rockwool slabs, coco coir etc in gutters and often dumped after a single run...

Most applications these days are NFT, and/or recirculated.... at least up to the point where they can't be topped up.... then they're dumped...

With modern temperature control methods this is way less often than previously.

Maybe the problem then is that the flow is way too fast?

I think the oxygenation provided by the higher flow rate would only be beneficial .... flow height could be a factor.... but I still think it's a nutrient problem.....

The oxygenation might be a good thing but the battering the roots are subjected to might knock off all the root hairs which would basically destroy the plants ability to take up nutrients.

Smile Les

300l/h is only 5l/m........ I hear you but I don't think it's the problem.....

any chance of nitrate offgassing post gb prior to nft?
Is there a way the flow rate can be slowed to perhaps reduce offgassing?
Do u have the ability to divert water post bio to both nft and gb pre sump? Even say only one tray and one gb for trial purposes.
I would suggest opening ball valve in return line directly back to ft to reduce flows, but would think this would still have some sort of offgassing effect so pointless.
On the iron chelate, I use 2 teaspoons a month in 5000lts seems fine, no obvious nute deficiencies. Only other system addition apart from fish food was a quarter banana early days to each gb.

I thought Dan said the flwo rate was 2000L/min.

hehe..that`d be a raging torrent.
The water film is usually only a couple of mm`s deep in nft, so even 1-2 lpm would cover a fair old area.