Low pH in the apartment system, but growth is good

I checked out the system this week, and it seems to be doing well.  The brown algae in the water is slowly disappearing.  The veggies are growing well, though the strawberry seeds that I scattered in one pot don’t seem to be growing too quickly.  My friend hadn’t checked the chemicals recently, so I did while I was there.  The pH was very low (<6), but everything else looked ok.  The ammonia was 0.5ppm.  Nitrite was zero, and Nitrate was 160+ ppm.

I added 6 capfuls of API’s pH up.  I decided that I didn’t want to rely on my friend checking the pH and adjusting, so I added enough pH up to bump up the pH to around 7.  Normally I wouldn’t want to raise it more than 0.2 per day, but I didn’t want to risk losing the bacteria and have to re-cycle the system.  My friend added a little water the next day, and checked the pH.  It was about 7 – 7.2, which is ideal.  Hopefully this weekend I can visit for a few hours to clean the canister filter, and plan out new fish that we want to put in the fish tank.  We’d also like to mount some small lights that we have onto chains above the grow bed.  Another issue is that the water draining is somewhat loud, so I want to figure out a way to muffle the draining water.  Here’s some pictures and a video from my visit to the system.