pH adjustment question

[etncrew]

The reverse osmosis water i use is just a bit too acidic (6.2 ish), and has left my soil a bit acidic too. What would the best method of raising the pH be. I'm a couple days shy of being a week into 12/12.

Garden/dolomite lime? Epsom Salts?

 

[Retardo Motabon]

Are you in soil or peat? What is your pH from runoff or how do you test? I ask because if you are in a soilless mix and just a tad low 5.7 or 5.6 you might want to try to bring your pH back up by using a high pH water or feed. If it is lower you probably want to add a little lime. I had a dropout a while back and figured I'd use basic water or feed and counteract the acidity. IT didn't do it, just made the mix more unstable. I added about a teaspoon of hydrated lime per 3 gallon pot and it took me right back to 6.0. Hydrated lime is much more powerful than dolomite lime so be careful with it if you choose to sweeten the mix as the pH might swing too high if you over do it. Dolomite is more gentle. Only mix in a little at a time as you'll have a very hard time dropping from upper 6's to 5.8-6ish If you over do it. Use just enough to stabilize. If you are in soil it's a little safer if you go a bit high. Don't feed until you straighten the pH out or your symptoms will just get worse. Nitrogen based ferts are acidic. If they need to be fed while you straighten out the pH just foliar feed.

 

[etncrew]

thanks for the reply RM!

i'm in soil, just your standard potting soil plus perlite and vermiculite for good measure. my pH from runoff today (i fed them today) was 6.3. the reverse osmosis water i use has a low pH to start with (6), and i can't give them enough nutes to make the feed mix more basic because that would be a quite a bit more than the directions suggest. sorry i'm sort of stoned right now so i'm not sure if this is making sense.

i think i'll just use a bit of dolemite lime, pH doesn't need to be adjusted very much i just want to make sure to straighten things out so this doesn't cause me too much grief down the road

 

[onelov]

i have the same prob with hydro...

my r/o is 6.1- 6.2ish it was fine at first but after i starded adding nute's it's 5.3-5.5 i just use ph up......

you can add lime, but then your stuck guessing how much and checking your run off of when to add more......
i'd add a ph up when you feed......

 

[Daemon]

^^That's what I do, and I'm in soil as well.

 

[etncrew]

can i just use pH up for a freshwater fishtank or something like that? i don't live in a very large city and i don't know of a hydro shop here. plus i'm relatively young (mid 20's) and i always feel so heatbag going into grow shops that cater to straightlaced christian types growing tomatoes around here

 

[etncrew]

anyone?

 

[onelov]

my buddy use fish tank ph up n down.... i have never done it bet hiz are fine....

they make a powder that's 6.2 stable thats what he use's

 

[etncrew]

i'm in soil though. i'm just wondering about using it in my nutrient mixture to offset the pH of the Reverse Osmosis water

 

[Retardo Motabon]

Aquarium pH up will work but don't use a buffer such as 6.2 as mentioned if you are in soil. When you say standard potting mix I think soilless mix (peat moss & perlite). If you are in soilless use lime at less than suggested rates and work your way up to your desired pH (I like 6.1). If you go full dose right off the bat you might push the pH too high for the rest of your grow as you'll have to flush em way to hard if you need to drop it back down. Most ferts drop your solution pH. You don't need to feed that much I go about 1000-1200ppm tops. I still end up flushing. Use less nutes and your soil pH will be more stable. I start at 7.5 adjusted water and after mixing nutes the solution drops to about 5.3 pH. I level it back to 6.1 and feed. I don't recommend straight r.o. alone it seems it can destabilize your soil chemistry. It might be helpful to mix your r.o. with tap if the tap water has a higher pH. You may not need cal-mag if you add tap to the r.o. as well.

 

[etncrew]

if i could give you a k+ for that i would retardo motabon!

Its not just peat moss and perlite it has some soil in it too, i added extra vermiculite and lots of perlite....anyway, i want my pH to be 6.5

my Reverse Osmosis water is 6.0

tap water has a pH of 8.0

Reverse Osmosis plus 1/2 strength feed has a ph of 6.1


i think i'm going to use a bit of tap water as a buffer. its extremely hard so i won't have a cal/mag issue going on....do i have to worry about chorline though?

either way they don't seem to mind...i'll post some pics today

 

[master shake]

dolomite lime will raise the pH. I don't know how it works in mixing with nutes but you can top dress and water in I believe. 1 tbs/gallon of soil. doing this should also remove the need of adding cal and mg. You could also buy some spring water or use tap water to bring it up.

 

[Retardo Motabon]

Sounds good ETN, with that basic tap h2o added to your r.o., your good to go!
Just make sure you follow the measurement for the type of lime you are using. There are several forms out there dolomite and hydrated being most available. Hydrated is much more active so you need less. My grips go so quick i like to use the hydrated as it buffers more quickly, you just have to make sure you use less.

 

[etncrew]

Agreed. From what I've heard and read, dolomite lime seems to take forever to work so you can add to much before you've even realized it. I always try to underwater (a tiny bit) and underfeed, as opposed to overwatering and overfeeding. anyway, the girls look good....i'm going to snap some pictures.


i wonder if i should trim them any, going to weigh the taller one down......pics to follow soon for anyway that cares here
ETNCREW's Grow Diary

 

[tree&leaf]

The reverse osmosis water i use is just a bit too acidic (6.2 ish), and has left my soil a bit acidic too.

Time to replace the RO filter then? RO water should be 7.0 out of the RO machine although it will be changed by adding tap water.

6.2 is fine don't mess with it, 6.2-6.5 is the optimum ph range.

 

[Retardo Motabon]

R.O. is kinda unstable, pH meters have a hard time reading it as it's so empty. My R.O. is always 6.5 but thats by my meter. If you drink your r.o. you'll know when the membrane should go.