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HYDRO Ph problem

R

Rj420

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Is it ok to adjust the ph in the reservoir while the plants are in it 5gal dwc? My ph is consistently creeping up between my reservoir change (1 a week). I’m starting to notice a bit of yellowing on some new leaves. I’m using de-gassed tap water with a starting ph of 7 before nutrients (perfect 5.5 after nutes). I’m sure there is a lot of dissolved solids in the water that is giving me some buffering effect during reservoir changes. As the girls grow and get bigger do they affect the ph more? Will it be ok if I have to adjust the ph down a couple of times between reservoir changes?
 
Yes. It’s ok. Just to maintain. If it’s swinging beyond1.5-2 then I would consider doing a reservoir change. If you are adding to adjust from 6.5 down to 5.5 that’s all good.
Btw, chlorine does not gas off from modern day water. If you want to remove it, try a basic charcoal filter (like the one that Brita makes).
 
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Howdy Rj420, It is normal to have the pH change as the plants take up the nutrients from the water, especially when the plants are growing rapidly. I have had the pH change from 6.0 (at the feed) to over 7.0 by mid week (when I top off the reservoir) especially during the vegetative growth period. Only when the pH stays outside of the range of 5.5 to 6.5, for long periods of time, will it harm the plants.
 
The ph seems to be buffering up about 3 days after I change the reservoir. I put a little ph down in the reservoir to get me through until the next reservoir change. I’ll keep results posted
 
Lately I've been doing a partial add back program. I add 5-10 ml of Maxi Bloom to my topping water to drive the pH down and maintain a more consistent concentration of nutes. I'm running at 600-650 PPM with my Blue Dreams and they're pretty happy.
 
Rj, I grow hydro and I check the pH every morning. Mine starts low so I add pH up and then it lowers during the week. As long as it stays between 5.6-6.2, I leave it alone.
 
Should I have to be adjusting the ph down 1 point every other day in between reservoir changes? Are the plants using all the nutrients out of the reservoir and changing the water back to its 7.0 neutral state? Should I be upping my nutrients more? I’m using advanced nutrients ph perfect sensi grow a+b veg. When I change reservoir and add nutrients the ph is a perfect 5.5. 2 days later it’s almost a 7.0 ph, I adjust the ph back down and 2 days later it’s up again. I’m only using 6ml per/ gal right now. The guy at the hydro store said I shouldn’t go over 6ml/gal, but advanced nutrients feeding chart recommends using 15ml/gal during week 4 (which I’m in now). Am I just under feeding my girls? They are growing incredibly fast and look nice and green. So I don’t know if I should just keep doing what I’m doing and not fix it if it isn’t broken and they are thriving? I only have 2 more weeks before I’m changing over to bloom.
 
My pH starts low after I add my nutes, so I raise it. It lowers over a day or two, then I throw in some more pH up. The roots absorb different nutes at different pH levels, so it's fine to let it fluctuate.

Don't add more nutes: just once a week. And be careful not to overdose the plants on AN nutes: I used to use those, and I always used way less than they recommended. I had to flush about every 3-4 weeks using AN or I'd get nutrient lockout. I strongly recommend that you give them a 24 hour flush before switching, and maybe another around week 4-5 flower. They LOVE the break from nutes and then the return to nutes.

Learn how to let the girls tell you what they need. The more time I spend really looking at my girls, the better I read all their signals. If your girls are growing fast, standing right up, looking happy, then you are giving them what they need. Yes, they will need an increase in nutes through around week 5 in flower, which is when I start to slowly lower nutes. Plus I sing to them. They love that.
 
Girls are looking good. Going to start adding orca microbes starting week 6
 

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You can.... I find it’s unnecessary though. I just give them the bloom nutes with no flush prior to flipping them. Everything turns out fine for me.
 
I’m no pH expert, but I think there is a change in pH as the water temp changes. My issue was the pH climbing as the water temp dropped because I was using tepid water temp and the water in my tent was about 10C cooler. I’ve started using just cold tap water and now my pH seems to be more stable after a very small temp change over 24 hrs.
 
The value of Kw (Water ionisation constant) and pH with increasing temperature is I think what you are referring to and that's correct. But I believe the range of temp required to make a full point change would only play a small part in the drifting ph. I fought this for years and determine to just adjust the ph after a nutrient change. Check it every morning and adjust to keep it between 5.5 and 6. I seems to stabilize a few days before change out and saved old brain cells....:-) from worrying about why.
 
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