I am new to the forum, but am looking for answers to my pool woes. Have an inground 42,00 gal vinyl liner pool. Had no problems until last summer when suddenly it started taking chlorine like mad. Treated for yellow algae and did ok until pool closed.
Used a cartridge filter, but switched to sand filter this year for ease of use. Have used dichlor for 4 years with no problems in cyanuric acid until opening this year. When opened, pH was high as usual, came down as we shocked until it plummeted. Again was chewing up chlorine. 100 pounds of dichlor in first two weeks. Cyanuric level was 95, alkalinity low, chlorine hard to get a level to mainitain.
Drained about 3 feet of water, treated with bicarb and borate and refilled, switched to calcium based chlorine. Cya down to 65, getting chlorine to stay for at least a few days. Yeah! Until it rained 5 inches. Back flushed, double shocked (no dichlor), noticed powdery precipitate at bottom of pool and again can't keep chlorine.
Used copper based algicide in case it was mustard algae again (common in this area).
Todays readings (at pool store): pH 7.3, free chlorine 0.6, total chlorine 1.3, copper 0.9, cya 100, alkalinity 210, hardness 200, no measurable nitrates.
Any ideas (considering switching to salt, but don't want the expense yet, but chemicals are adding up quickly!!)?????