Yeah its a possibility. If the ppm goes down again ill give her a good feed and see how she responds.
That's a good way to create a lockout and that might be what you're looking at - is that a Ca issue or a K issue?
When plants are given fresh nutrient solution (hydro), these chemicals are taken very quickly, in the first few hours.
If you top off the nutrient solution with fresh nutes, you might create problems because the plant will take up Mn, N, P, and K from the replenished res even though it already has those chemicals in the plant. That can create an imbalance and, therefore, a lockout.
Rather than top off with full strength nutes, you can do "add backs" of RO water until the amount that you have added back >= the volume of the res OR, per Bugbee, you can add nutrient solution that's been diluted to 25% strength. Bugbee uses Hoagland's solution.
If you're adding back RO and if pH is swinging and if your EC has dropped significantly (50%), if may be that the nutrient levels are so low that they can't buffer pH changes. At that point, swap the res.
I've been trying to get an answer for "how often should I swap my res" because I grow one plant in a res that holds 28 gallons of nutes. It's ludicrous to change it every week when the plant is small so that's why I started asking the question. The "add back until water added = res size" and the Bugbee-add Hoagland approaches seem to be the best options to me.
This copy/paste is of an Excel document that I put together to try to understand how PPM's change as reservoirs are depleted. It's a work in process but it might provide a little background.
What it helped me understand is that even if a res drops from, say, 768/500 PPM (meaning 768 PPM on the 500 PPM scale) to 560/500, there's still a lot of chemicals left for the plants to take up.
- yes not a bad idea, it was looking slightly frothy today which i didnt like the look of.
- syringe from bottle A then B im pretty careful to do the right order
- 10 gallon bucket
- it was 5.9, went up to 6.4 now down to 5.7. The damage looks like pH issues possibly. Wanna see if shes happier at a lower pH.
Thanks for responses!!
pH will tend to rise as nutes are taken up but, especially in flower, it's completely normal for pH to drop gradually, as well. If you have root rot, pH will drop but there's no reason to get wigged out if pH drops - it's an indicator that something is happening and a grower needs to find out why. I've done five auto grows and, even though they were different strains, pH dropped for a few days after a new res. That's just cations vs anions.
In DWC, a pH of 5.8 is widely considered to be optimal.
"gunk" - that could be nutes precipitating out of solution, which is common, or it could be plant material of some kind. It's worth it to see if it's the former, which is OK, or the latter, not OK.
