- Oct 4, 2018
- 89
- Pool Size
- 25000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Autopilot Digital PPC1 (RC-35)
After enjoying several seasons of trouble free pool using the methods on this forum, I'm having a problem with Iron that I can't seem to overcome. My iron test strips show that there is no iron in the municipal water or in the pool water, but that is clearly not true. Last season I started having an issue with iron deposits on the liner. I removed with ascorbic acid, used sequestrant, and also used a CUlater. It held up okay, but it seemed to get worse over time. This spring when I opened about 3-4 weeks ago, the stains were back in force. I used the AA treatment to dissolve the stains, then I performed a water exchange, which managed to remove about 50% of the salt in the pool according to my test kit. I resalted the pool, and balanced the chemicals, though the ph remained on the low side, around 7.0 occasionally drifting below 7, chlorine demand was high. A week ago I added some washing soda, to bring it up a bit. Last night I saw a totally clear pool, and a pH around 7. This morning I noticed the iron stains coming back, the pH had jumped to 7.8. My first thought is the AA finally had broken down. But it's difficult to keep the pH from ever going up to 7.8 for an entire season, there must be too much iron still in the water. I didn't have muriatic acid on hand, but I did have some dry acid which I added to quickly bring it down.
pH - 7.3
TA - 70
CYA - 30
FC - 3
CH - not tested
Solutions from TFP I've considered:
-Drain and fill: This did not seem to do the trick, because I cannot drain the pool completely since it is a vinyl liner pool, and it seems likely there is iron in my fill water.
-Reverse osmosis: I cannot find a provider in my area.
-Truck in water: Seems not very practical since I cannot drain the entire pool.
-Precipitate and filter out: Some have had success, but only with visible iron in the pool. If I precipitate the iron by raising the pH and chlorine, much will likely stick to my liner. Could this work?
-Specialized filters, such as green sand filters, it seems difficult to accomplish on a large scale, concerns about manganese contamination appear in the wiki.
-Precipitate and floc: Floc is not popular on the TFP forum. However a number of sources suggest a common strategy is to precipitate the iron and then use floc to sink it and vacuum it to waste. Seems plausible this could help.
What do you think I should try?
pH - 7.3
TA - 70
CYA - 30
FC - 3
CH - not tested
Solutions from TFP I've considered:
-Drain and fill: This did not seem to do the trick, because I cannot drain the pool completely since it is a vinyl liner pool, and it seems likely there is iron in my fill water.
-Reverse osmosis: I cannot find a provider in my area.
-Truck in water: Seems not very practical since I cannot drain the entire pool.
-Precipitate and filter out: Some have had success, but only with visible iron in the pool. If I precipitate the iron by raising the pH and chlorine, much will likely stick to my liner. Could this work?
-Specialized filters, such as green sand filters, it seems difficult to accomplish on a large scale, concerns about manganese contamination appear in the wiki.
-Precipitate and floc: Floc is not popular on the TFP forum. However a number of sources suggest a common strategy is to precipitate the iron and then use floc to sink it and vacuum it to waste. Seems plausible this could help.
What do you think I should try?