Quote Originally Posted by immortal420
My EC went from 1285 to 1900. I change the reservoir once a week, I don't top-up, should I?

ppm went from 850-950.
Yes you should keep the rez topped up with ph water. The flux in ppm's can change the PH. If ppm's go up your plants are drinking more water. Remember the plants are also pissing in your rez. LOL. Giving off waste material too. That why your doing right by changing every week.

Let's say you have a 5 gallon rez. When you top up with 5 gallons of ph water or as I do just top up with R/O which is 7.0 for me it brings the ph back up to 5.8 or 6.0. You have replaced the 5 gallons your plants drank it's time to change because of waste your plants gave off.

Top up with your water and I bet the ph comes back up. The rez might of just got toooo low this time and ph went down. No big deal cause you sound like your on top of it and care about your crop. That's why it's hard to walk away for a long time unless you have the automated system and I bet I could screw up that if I did not keep a eye on it.