Even if you can't do RO, there are DIY methods you can utilize to manage this.

Since these drastic pH changes are caused by changes in the chemical content of the water, use ion-action water purifier filters. Get a large bucket, drill holes large enough to SQUEEZE some brita or pur or whatever filters in, seal them up tight with some sort of adhesive, set that bucket over another bucket (I drilled equal-size holes in a lid to allow the bucket to just sit on top while the water filters through to the second bucket below,) and pour your water in. The more filters, the more water filtered per minute.

Works with rainwater as well as long as you keep the bottom bucket sealed.
khyberkitsune Reviewed by khyberkitsune on . im done jacking around with ph problems i've got several grows under my belt some turned out fantastic and others kinda suffered a little. my biggest problem has been with ph (im a dirt farmer)my tap water changes so much it is hard to keep up with. i have used the drop test kits with varied success over the years and have tried a few different ways to adjust the ph of my water. im at the point of disgust with this round. tap water has been jumping around from 7.5 to 8.5 all summer. i do let my water stand for a day or 2 before using Rating: 5