Yesterday I did a drain/refill of my plaster-lined pool to reduce high CYA and CH levels. Wrote about that in another thread here: Refilling now - next steps?
Due to high CYA, I have been running pool at high chlorine levels for a couple of months, between 13 and 16 ppm, since taking ownership of the house/pool. During that time, I had developed some nasty orange/brown staining on the walls and steps. The stains didn't respond at all to a trichlor tab, so not algae. They also didn't really respond to manual brushing.
Yesterday, when the pool was draining, I crushed up a vitamin C tablet and brushed it on one of the stains on the steps and, like magic, the stain absolutely vanished.
I had a LONG time to sit and watch the pool drain, so I figured hey, why not scrub down the walls and floor of the pool with a dilute vitamin C solution and see what happens? Amazing results. Basically I crushed up a handful of vitamin C tablets, maybe 10 or so, then added about a cup or so of water. Using a small scrub-brush, I slowly and methodically applied this liquid to every square inch of the pool that was above-water. Didn’t brush hard, just spread the stuff around and then let it sit for a few minutes before rinsing off with clean water from the hose.
This was miraculous! All the stains were just gone. Amazing.
At this point, after some reading here, I am guessing the stains were iron deposits, maybe due to extended period of high FC (due to high CYA) and a period where pH was probably too high, as it was hard to monitor pH with FC hovering around 15 ppm.
Anyway, today, on refilling the pool, the water had a slight greenish tinge to it. In my other thread, Richard320 guessed that maybe it was iron in solution and that the orange iron was causing a green cast to the water. At this point, I’m pretty sure he’s right.
I’ve been running my skimmer with a sock, and after about 3 hours of circulating the greenish water, the sock was stained orange – probably iron bits in solution getting strained out? The pool is clearing, slowly.
BUT, my FC is only at 3 ppm for now. CYA is probably very low, as I removed and replaced about 95% of my water with city water, so I’m guessing CYA is around 10 or so.
I want to add some chlorine, just to keep algae at bay since CYA is low and it is hot an sunny, BUT – I’ve been reading that adding a slug of chlorine to a pool with iron in it can cause all the staining to recur – the LAST thing I want since I spent several hours working the stains off the walls yesterday.
So, do I need to add some kind of sequestrant to keep the iron in solution, before I add chlorine? I don’t know anything about this – any insights would be so much appreciated. I’ll attach some photos if I can figure out how.
Photos:
1. Scrub in progress with Vit-C. Left side of steps done, wall at right done, remainder untouched:
2. Vit-C Scrub in Progress, lower portion at waterline untouched, upper wall complete:
Photo 3: Water after refill, green-ish tinted water
Photo #4: Orange stuff in skimmer sock after 3+ hours of regular pumping/filtering
Due to high CYA, I have been running pool at high chlorine levels for a couple of months, between 13 and 16 ppm, since taking ownership of the house/pool. During that time, I had developed some nasty orange/brown staining on the walls and steps. The stains didn't respond at all to a trichlor tab, so not algae. They also didn't really respond to manual brushing.
Yesterday, when the pool was draining, I crushed up a vitamin C tablet and brushed it on one of the stains on the steps and, like magic, the stain absolutely vanished.
I had a LONG time to sit and watch the pool drain, so I figured hey, why not scrub down the walls and floor of the pool with a dilute vitamin C solution and see what happens? Amazing results. Basically I crushed up a handful of vitamin C tablets, maybe 10 or so, then added about a cup or so of water. Using a small scrub-brush, I slowly and methodically applied this liquid to every square inch of the pool that was above-water. Didn’t brush hard, just spread the stuff around and then let it sit for a few minutes before rinsing off with clean water from the hose.
This was miraculous! All the stains were just gone. Amazing.
At this point, after some reading here, I am guessing the stains were iron deposits, maybe due to extended period of high FC (due to high CYA) and a period where pH was probably too high, as it was hard to monitor pH with FC hovering around 15 ppm.
Anyway, today, on refilling the pool, the water had a slight greenish tinge to it. In my other thread, Richard320 guessed that maybe it was iron in solution and that the orange iron was causing a green cast to the water. At this point, I’m pretty sure he’s right.
I’ve been running my skimmer with a sock, and after about 3 hours of circulating the greenish water, the sock was stained orange – probably iron bits in solution getting strained out? The pool is clearing, slowly.
BUT, my FC is only at 3 ppm for now. CYA is probably very low, as I removed and replaced about 95% of my water with city water, so I’m guessing CYA is around 10 or so.
I want to add some chlorine, just to keep algae at bay since CYA is low and it is hot an sunny, BUT – I’ve been reading that adding a slug of chlorine to a pool with iron in it can cause all the staining to recur – the LAST thing I want since I spent several hours working the stains off the walls yesterday.
So, do I need to add some kind of sequestrant to keep the iron in solution, before I add chlorine? I don’t know anything about this – any insights would be so much appreciated. I’ll attach some photos if I can figure out how.
Photos:
1. Scrub in progress with Vit-C. Left side of steps done, wall at right done, remainder untouched:
2. Vit-C Scrub in Progress, lower portion at waterline untouched, upper wall complete:
Photo 3: Water after refill, green-ish tinted water
Photo #4: Orange stuff in skimmer sock after 3+ hours of regular pumping/filtering
