Cycling - Water Chemistry

[hidroron]

Am a "newbie" and have questions about cycling. Fish tank is 950 liters and grow bed 500 liters. Start up on system 30 days ago. Using goldfish to get everything started. NH3 dropped from 12 ppm to 0.25 ppm on day 20. NO2 prior at this time was 5-6ppm and NO3 was 20 ppm. From day 20 to today day 30 pH keeps rising to 8.8, and NO2 is 10+ and NO3 is approaching 100. Levels were so hi I had to dilute sample 1:1 with RO water to get accurate reading. Fish seem fine (they are hardy little guys!) And plants - spinach, lettuce, arugula are growing very well.

I've also lowered pH periodically by adding HNO3 to get it to 7.6 but keeps rising.

Is this normal?? I keep expecting to wake up one morning and find the fish all dead. Am planning on eventually raising tilapia but am sure they aren't as tough as goldfish.

Any comments/suggestions would be appreciated.

[nwestwood]

Yes the PH does go up when cycling and it will cycle faster if you let it go up, the fish like a higher PH as well as the bacteria we care about. Once cycling is complete and your nitrites drop down, then you can manage the PH for a balance between the fish and the plants. Plants like 6.8, fish like it higher. Most systems will bounce in the 6.8-7.4 range to keep the plants happy after cycling is complete.

[hidroron]

Thanks much! I won't worry about the pH right now. I'm more concerned about the very high NO2 and NO3 levels. But I guess I shouldn't worry about these either since the fish seem very happy and energetic, and the plants are growing like weeds. I'm incredibly impressed, how forgiving and self adjusting the whole system is. I guess I'm too impatient and want to get some Tilapia started. Are they as forgiving as goldfish?