My 30k gallon pebble-tec pool has nice clear water but I am constantly doing the dance between minimum FC levels, ph balance, and metal staining. I use Borates and the pH seems to hold steady at 7.6-7.7 (best I can tell - I find the Taylor color matching to be tricky, wish there was a better test). I add acid about once a week but it always seems to settle back to 7.6-7.7 after a day or so. It is currently very hot here in New England and my pool is in full sun. I am running my SWG at 90% and FC is holding at 4-4.5 with 0 combined (Taylor DPD kit). My CYA is around 60, so I need to maintain FC around 4, and I live in fear that it will drop below this and I will get algae. I have some light brown staining here and there that does not brush off, which I believe is Iron staining. I fear that more will come out if I turn up the SWG, because it will cause pH rise. Also, I'm not sure how much more capacity to generate FC the SWG has, it is at 90% already. So my question is... should I add some Polyquat 60 as an algae prevention insurance policy as we head into a heat wave this week? Any downside from a chemistry standpoint? I have read here that polyquat 60 can make the pH hard to measure because it interferes with the indicator... is this true? pH balance in my pool (SWG and constantly aerating spillway) seems to be really important or else I get metal stains and scale. I did use some Metal Magic early in the season, and I think it has helped prevent staining... but I likely need to re-dose and the bottle says you have to drop your Chlorine to under 3 to use it. I am afraid to do that with the current weather. My phosphates are sky high (like 4-6k according to pool store test, I don't have a Taylor kit for this), which I blame on the Metal Magic. But it seems like phosphate removers would defeat the purpose of having metal sequestrant in there. At the same time, I must keep the FC in range or I am a perfect host for algae. So... chem geeks... what do you suggest - add the polyquat? Add metal magic despite higher FC? Attempt phosphate removal (this will be a PAIN given how much sequestrant it will take)? Water is perfect right now... but I'm dancing the dance and it is giving me anxiety!!