Ph rising

I am growing my plant in a 2 liter tank. The tank is enclosed in a dark bucket with a lid over it. The lights are on a 24 sched with a 400W Mh. The temperature of the air is 74 degrees and it fluctuates from that to about 80 though out the day. When I add my nutrients I adjust the Ph to 5.7 and then I add it. I am using a miracle grow 30-10-10 solution mixed at 75% percent recommended strength. She is a little over a month old, she is developing secondary leaves at the stem. I have been checking the Ph daily but every 24 hrs the Ph rises back to almost 7, sometimes a little higher. I keep adjusting it every day, I change the res every 3 days. One of the older set of leaves had tiny little light green spots that turned into little yellow dots. Now another set is developing small light green spots but not nearly as bad as the previous set. Why does the Ph keep rising? Any help would be real appreciated. Thanx

Add the nutrients AND THEN adjust the PH.

as water evaporates, pH- or parts hydrogen- changes. I discovered the pH of water i was leaving out over night to de-chlorinate rising, started a similar thread, but i'm not familiar with using a reservoir system... would it be possible for significant water to evaporate?

First off, you are not using a hydro nutrient, which have formulas that help to buffer pH in a res.

Try mixing your nutrient with your water, then let it sit for 24 hours, then adjust pH and use.

HTH

It will still rise as plants absorb nutrients and leech salts but it shouldnt be that much in a day.

Thanks guys. Any clues whats wrong with the leaves??

"PH Wand" -METER YM-2005