pH fluctuation during final flush

I cannot get my pH to stay stable during final flushing. I am using ebb&flow watering 3x a day. I changed the 20 gal res last night to plain H2O w/5.8pH and let it run its course 2hrs before lights off. To make sure things were good, I checked the pH this morning before watering and it was 6.8. I adjusted back down to 5.7, and let the system do its morning watering. Lunchtime rolls around and same thing, 6.8pH. I dumped the res at this point thinking that maybe the salts coming off during the flushing was wacking out the pH. I have new water pH'd to 5.6 now in the res for tonights watering, but I cannot do this for five more days... Any suggestions?

Just let it do it's thing. You are flushing with plain water so lockout is not a concern since there are no nutes.

It will continue to change each time you flood due to nutes left in the growing medium

I let the pH fly last harvest, and all of my plants' leaves seemed to turn brittle within a day or two. It made it easy to clean because i could just run my hand up the buds and all the leaf fell off, but this didn't seem to be correct. I know some fan leaves will die, and the colors will be off on some of the leaves at the end of harvest, but I haven't heard too many people describe anything crispy. Everything has gone awesome up untill this point, don't want to screw it up now...

Well.....don't know what to tell you - I have never had a problem.

what medium you are using?

Tokey21 said:

I let the pH fly last harvest, and all of my plants' leaves seemed to turn brittle within a day or two. It made it easy to clean because i could just run my hand up the buds and all the leaf fell off, but this didn't seem to be correct. I know some fan leaves will die, and the colors will be off on some of the leaves at the end of harvest, but I haven't heard too many people describe anything crispy. Everything has gone awesome up untill this point, don't want to screw it up now...

Click to expand...

Angel's Bandit... You may be right, I had never flushed before last harvest, and never had the problem. I guess because this was the only thing that had been different from previous grows, I assumed it was caused by the flushing.

Cack... I start them in 1.5in grodan rockwool cubes. At about two weeks they go into small pots with hydroton. The pots are increased twice more throughout the grow, always using hydroton.

I put my rockwool cubes straight into 5" net-pots with hydroton once they show roots, and never change pot size durring the grow.

The less you have to mess with things - the less chances you have to screw something up.