I have a 180 gal community tank with live plants, nothing difficult to grow(java ferns, anubius, water sprite) The tank gets 10 hours a day of light plus natural light. I was adding Seachem Excel and Iron to the tank once a week , when I did water changes. Everything was fine, PH was good all other levels good. I increased the dosage of Excel and Iron and now I find my PH is stady around 6.2-6.4 and my nitrates are up. My plants look bad and new growth doesn't stay green for long. My question is....does Excel lover my PH like CO2 would? Would the lower ph harm my bio filters to make the increase in my nitrates? If the answer to the first two is no, how do I safely adjust the PH towards neutral?