CalMag is not used to change the PH of anything. Its just a calcium and magnesium supplement. Thats it, thats all. If you have a deficiency with one of those two, then yes, it can correct it. But if you just need to get your PH right, then you will need a PH meter and some PH up and down. You can get all 3 of those (They come together in a small bag) for about $15 bucks from just about any hydro store.
What makes you think you have a soil PH problem?? If every time you water, you first adjust the PH to 6.5, then thats what the PH of your soil should be, unless you over fertilize and never flush. So flush the crap out of the soil with 6.5 water and you'll be good to go. Im am curious to know why you think you have a soil PH problem.
LoL. Yeah man... they exist. I was just wondering how you came to determine you had a problem with the PH of your soil. Some people buy those crappy soil PH probes that you stick in your soil to read PH. Those things dont work worth a shit. So your testing your runoff..?? If its coming out that low, then it sounds like you may have a build up of nutrients, and should flush for a week. Set your water to 6.8 and flush with that for a week and see how things turn out. Dont do 8.2 though. That can cause a portion of your soil to be too high, while the other portion below is too low. So keep it at 6.8 with no nutrients. Then when you start back again, use a super light nutrient mix. like 1/8 strength. The low strength nutes will help to remove salt build up even more. Or you can buy some Clearex by Botanicare and run that through once or twice and see what happens.
na, I have a 100 dollar pen thats solid in calibration solution , i know its working this ph thing has got me all fuc*ed up tho. I have 3 gallon pots should I buy some bushdoctor and run 9 gallans per plant??? (damn thats alot) phed at 6.8? I only nuted once at 25% and I got the same runoff as when I didnt nute.
Get the lime, use the lime, end of story. ~$5 for a 40lb bag at Lowes or similar. Use 2tbl/gallon of mix, or 1cup/cf of mix. I don't pH anything going into my plants, water, teas, nutes, nothing. Bottled cal/mag will not do squat for your soil pH, neither will pHng water or nutes, except very temporary. Wet
Lime is high in magnesium and calcium and could worsen the problem, so hold off on that idea for now, but then again, it could fix the issue. I'll go back to the lime thing. First of all.... are your plants even showing any negative signs?? Pictures would help a whole lot. What type of soil did you start off in? Is it new soil? Or has it been used before? What type of water are you using? And what nutrients did you add the one time you added them?
You should be fine man. Im assuming your plants arent showing any negative sign, correct?? Like the saying goes.... If its not broke... dont fix it. If your plants are showing negative signs, then post a pic and I'll be able to help you out more. But your in Ocean Forrest, which I think is pretty good soil. Dont flush anymore, if you already have. You'll just be washing out nutrients that your plant can use. There's no way you can have a nute/salt build up. Just keep watering with 6.5 PH'd water and things will turn out fine. If your leaves start to turn light green, then give them a heavy dose of your Grow Big. 25% strength is pretty low. Fox Farm isnt very concentrated.