Just noticed something rather odd..
Since last night, I have been fighting the pH inside the res. Couldn't figure out why it was jumping to over 6.5 when the solution I was adding was 5.6. Every time I added more solution I would have to drop in pH down an hour later.
So naturally I assumed the problem was in the res, and gave some thought to doing a flush. Thing is, I just did a full flush a few days ago... So on a whim I checked the fresh solution I was adding to the tank. It was pH 6.8.
What I don't understand is how it changed. It was sealed in a plastic bottle.
Normally, I keep the solution in the tent so it will be at about the same temperature as what is already in the tank. It's in a clear bottle and under the full brunt of 20 hours a day of the grow lights.
I am wondering if the light somehow contributed to this?
So I've thrown away the container I was using and now with a new bottle, I've mixed 2 litres of 5.6 pH. I'm going to check it in an hour to see if it's changed. Honestly it never occurred to me to check the already mixed and adjusted solution, so I wonder how long this has been going on... Any ideas?