EC readings going up

[Spit3943]

Hi folks,

I've noticed the EC readings in my nft set up increase without me doing anything. Do the plants expel anything into the water to do this?

I have a 100 litre nft tray with 4 plants (1.2m x 1.2m) 600 w hps
I use canna hydro a and b and increase over time to suit the plants. I try to keep a steady reading of around 1 - 1.2 but I've seen this increase to 1.6 on its own

Been growing for a while now. It's not really caused any problems as far as I know, just curious as to what's going on.

Thanks

[Obi-Wan]

is your water volume decreasing along with the rise in EC? If so I would say it is normal for this to occur, but is normally a sign that your starting EC is too high. How old are your plants and how big are they?

[Campesino]

Interactions with the plant should not affect the EC of the nutrient solution. Transpiration and evaporation are the main causes of EC going up. This is why you should top off with lower EC water than you use when you clean-out and refill. If you top-off with full strength nutrient solution, it will make EC climb.

As Obi-Wan suggests, you should probably notice lower water levels as a result of this water loss.

[Spit3943]

Hi, cheers for the responses folks

Yes, the water level also drops. The plants are in there for the whole flowering and flushing stages so they get as big as they can

[Campesino]

Yes, exactly.

So, I recommend measuring EC before you top-off and determine the strength of "Top-off" water that you need to add to bring it back to your target. "Top-off" water may need to be close to 0 EC if your plants are transpiring a lot.

Cheers

[Spit3943]

Brilliant, thank you