Few Questions - Ascorbic acid treatment/SLAMing

[Pharming]

First off this forum has been a life saver! Moved into a house last year with a pool AND a hot tub with zero experience managing either. I think I've done okay so far, but I do have a few questions for the experts..

So this year I did notice some iron staining on my liner and steps, confirmed with the vit c test. This morning my FC finally reached zero, I got my pH down to ~ 7.2, and I added a treatment dose of polyquart 60 as advised. This evening i proceeded to dump the ascorbic acid in, seemed to start working fairly well, however I am going to let it circulate overnight.

First question, I know I should wait at least 24 hours before doing anything, and then raise my FC slowly. What is the duration of action for the polyquat? Will it cover my pool for a good 48-72 hours+ while my FC gets back up to speed, or should I think about re-dosing at some point?


Second........I think this may have stemmed from me performing the whole SLAM process... I actually left my pool open throughout the winter, kept FC at normal levels, until it got freezing cold, then the FC may have dropped to 0 a time or two. (kept my pumps running while <32 temp btw) But I never noticed any algae growth at all. I did have quite a few leaves fall in that I did my best to stay on top of, so was not 100% pristine the entire season. So when it started to warm up I cleared everything out and SLAMed it. After that is when I noticed the staining, which as I understand can be expected from high levels of FC. This kinda has me questioning the utility of the SLAMing process in general. Especially seeing as how during this AA treatment you bring the FC down to zero, and then it is actually recommended that you NOT bring FC up very high for while....

Should you only consider raising your FC to shock levels if you have considerable algae growth? It seems that slowly raising FC to maintenance levels will be enough to safely decontaminate the water from any bacteria...



Third, the source of the metals........we have a vinyl liner pool, SWG, no heater, city water. I have no clue what was done before taking over the pool, but what could some possible sources be? I did notice a ladder that had some rusting on the screws. Would that be significant enough to spread through the water?

 

[pooldv]

First, it is better to maintain your FC above minimum for your CYA, [FC/CYA][/FC/CYA], at all times and never have algae grow in your pool. Then you won't ever need to SLAM. I switch to bleach in the winter and add a gallon every week or two or three as needed. FC consumption in the winter is very low.

I wouldn't wait 24 hours just to wait. If the stains are lifted and the pool looks good then start raising FC right away. Raise it 1-3 ppm per hour and test it often. The AA will use up the FC quickly at first. Keep adding bleach and testing often until you get to minimum, [FC/CYA][/FC/CYA], and it holds. Then maintain FC between minimum and target at all times thereafter.

While iron is much more common in well water it is also in some municipal water supplies. Some municipal water supplies get their water from wells also. You should be able to look popup the water quality report to see if there is iron present in the water. I suppose it is possible that the ladder added enough iron to the pool but I don't know for sure.