AA the second time

RPSalty

Gold Supporter
Jan 25, 2019
66
Land O'Lakes, FL
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite Pro (T-15)
It's been just over a year since "My Iron Stain Removal" thread. Since I have well water, I have staining again. The noticeable staining is really only on the drain covers. I removed them once and cleaned them with muriatic acid and looked good for a while, but the staining gradually returns. So, I am pretty sure there is a red tint on the plaster, just can't tell because this year I didn't try to treat local spots with muriatic acid. My metal treatment for the last year has been SC 1000. This year I am changing to The Purple Stuff. Currently SWG is off, and I have pH at 7.2ish waiting for the FC to get down to 0. I could add the remaining SC 1000 I have, that lowers the FC, but I'm not sure of any conflict with the Purple Stuff. For now, just letting the FC come down naturally.
 
It's been a week and a half. The result is great but not what I expected.

First - for all of the past year my choice of metal control was Orenda SC 1000, this year I am going to use The Purple Stuff.
Second - The Purple Stuff costs more; maintenance doses are higher and there is the (dreaded) phosphates. From what penetrates my grey matter, as long as I keep the FC/CYA levels in sync, phosphates are a non-issue. No phosphates with the Orenda.
Third - I backwashed after 7 days, and there was red in the discharge. I never had red in backwashing with the Orenda.
Conclusion - The Purple Stuff gets the red "out".

What surprised me was the AA treatment had little or no change to the bottom or sides of the pool, there was spectacular iron stain removal from the drain covers, the only place staining was noticeable. So apparently there was no staining on the sides and bottom. In the past I had tried concentrating muriatic acid in areas to remove staining, so the staining was obvious with all the spotting. During this last year, no spot treating, and I removed the drain covers and eyeballs to clean with Muriatic Acid as they got very red over the course of a few months.
Conclusion - The Orenda kept the red in suspension, but the red did attach to the plastic drain covers. Polyfil was ineffective.

On the balancing side, FC is starting to hold, I'm slowly up to 4.0 and using less liquid chlorine each day. SWG is still at 40%, which is the setting before starting AA. I've kept the pH at 7.2 and will continue up to 14 days. Alkalinity is 80. CSI is -0.38 so I want to get that up, but I'll wait until Sunday.

So far, no red. :cool:
 
As I've read, yes. The purple stuff bonds with the iron and keeps the iron off of surfaces. The SC 1000 is a chelant and also bonds with iron. The difference, as I understand, is the sequestration creates a larger bond than the SC 1000 and will filter out.

There are many posts from members way more versed about the science of this. I'm just going with it!
 
It's been two weeks and the pool looks great! I'm still having to supplement liquid chlorine but only a cup yesterday. The pool chemistry is in the recommended range.

I had reason to visit the pool store, so I took a sample. There results were different but primarily I wanted to know about the sequestrant level. I was low - 4 drops and the norm, according to them, is 10-12 drops. I will need to invest in my own test kit, I read LaMotte Sequestrant test is a good choice. Phosphates = 2000.

This page, Sequestrant - Further Reading, is hugely informative. The section about using a sequestrant has me wondering. My water source is rich in iron. If I were to monitor how much make up water was being added to the pool, would I be able to determine how much sequestrant to add? The raining season is approaching and if Mom Nature keeps my pool topped off, do I need to be adding a sequestrant? Is there a way to determine the need for a sequestrant before I see the staining?
 
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