rkymtnman
Well-Known Member
why not just make your own pH down (most used vs ph up) and it's way cheaper than adding nutes? for ph up, i use silica.
Nutrient Uptake
- Thread starter ElFuego
- Start date
rkymtnman
Well-Known Member
gotcha. well, day 6 of a dwc solution is sub par compared to day 1. dontcha think? i do for sure.
i used to run dwc buckets dtw just to optimize nutes.
Agree 100%.
futurebanjo
Well-Known Member
Interesting, can you just use a cheap acid like white vinigar or something?
"sub par" - No, I would not assume that. "Assumptions are the mother of all fuckups."
Just because nutes have been taken up from a res does not mean the res is not able to provide sufficient nutrients to the plant. That's the whole issue.
I've got 28 gallons of nutes in my res. There's no way that I need to change the res after the first week in veg. OK, that's a big res so what about 1 10 gallon bucket or 3 or 5? Or ten days, 12 days, or two weeks?
We don't know that the nutrient mix needs to be changed unless we get a chemical analysis or if we see signs of insufficiency or toxicity. We can just do it every week and a lot of growers do that. The nute companies love it. Think of the revenue change if growers went from weekly changes to bi-weekly. Ouch.
Anyway, check out this paper from Bugbee. One of the points that he raises is that when you top up, the nutes taken up most quickly may reach toxicity levels if you top up with full strength nutes. OTOH, if you use water, you're diluting the nutrients that are taken up more slowly. The "just right" approach is a replenishment solution that's a diluted version of nutes. Apparently using that approach, a res can last a long, long time.
Back in the day, it was purple microdot…
futurebanjo
Well-Known Member
rkymtnman
Well-Known Member
let's see what you would call this issue then;
your res has 200ppms each of n, p and k
each day, your plant eats 40ppm of n. what would you call your res on day 6? there are 0 ppms of n left. i'd call that sub par if not inadequate.
so the res is not able to provide any n to the plants. still not sub-par to you?
If the res isn't providing the nutrients that the plants need, then I'd swap it out.
But how would you know which nutrient without waiting for deficiencies to show?
I have to use ph up due to acidic well water to start and then nutes lowering it even more. I have to add a lot of ph up (potassium carbonate) to correct it. I hadn't thought of silica. That should keep me from adding excess potassium. Is silica stable or do you have to add it every day or so?
The only thing I can think of at the moment is to get the nute water tested.
rkymtnman
Well-Known Member
i've onlly used 2 of the 3 main sources of Si: potass silicate (which adds more K but does raise pH quite a bit). i now use sio2 from cutting edge solutions. which does raise pH but no added K. and then mono silicic acid which i've never tried.
Thanks a lot for this. I did a search and found a supplier locally. I'll call them up when they open.