Iron stains

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tko

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Apr 13, 2016
75
Portland/OR
Hi there: I've read a lot about how to remove iron stains (confirmed with a vitamin C tablet test). With my CYA around 30, I keep FC at 3-4 and pH around 7.8. It seems to me I'm seeing more orange spots on the bottom of the pool. Is the high pH making this worse?

The pool store said I had .1 iron and .1 copper in my water - is this reliable? The numbers don't seem that high given other posts I've seen. Trying to decide if I should embark on this mission: www DOT troublefreepool DOT com/sticky.php?s=2298

I just got done tackling an algae issue in our newly acquired pool which was unused for 3 years. I'm afraid to let FC fall - should I use an algaecide if I do take FC down? It seems there are mixed opinions.

 
Hey TKO.
There's a definite relationship with the SLAM process and metals being deposited on pool surfaces.

The higher your pH is the less likely metals will stay in solution - the more acidic(lower pH) the more free ions to bond to iron and copper molecules
Bleach is Caustic so Slamming will raise pH and subsequently under the right dissolved metal conditions cause staining on liners & gunite.

I'd advise against the whole pool AA treatment - far too many side effects.
If your stains lift easily with a bunch of vitamin C pills in a sock just take your time and clean while you swim, but keep your pH down in the 7.2-7.4 range.
after using a bunch of pills you will see FC drop, and possibly CC - don't get alarmed if your water started clear but has a light turbidity. The FC is being consumed by the free AA. Just monitor for a few hours and bring FC up gradually.

Pool store metal tests are unreliable at best and complete garbage for the most part.
They don't account for sequestrants in the water which are binding up copper & iron - which will drop out of suspension when pH goes high
 
TKO, as an alternate to the AA treatment, I've had past success with the Metal Magic sponge test and dosing to the level indicated by the test.

If you have metals, you need to sequester them anyway. I found that in my pool, the MM removed "fresh" iron stains virtually as well as AA without the shenanigans. Its not as "sure fire" as an AA treatment, but here's a link if you want to give it a try. http://www.proteampoolcare.com/images/uploads/MetalMagicSpongeTest.pdf
 
Right, it helps keep the metal in solution. High ph causes the metal to fall out of solution.

I've used different (recommended) sequestrants and in your case I'd recommend specifically the Metal Magic. Its seems to work best at byproduct stain removal, it requires less top up to maintain, you can get good guidance off that sponge test link I gave you (for free, no expensive sequest test needed) and its cheaper, eg. Check out Pool Chemicals, Hot Tub Chemicals and Supplies | Pool Geek

For Metal Magic, however, you actually need your ph a little over 7.5 for it to work optimally...it will bring the ph down a bit. So if you're going to use it, you don't need to lower ph as much.
 
Great to know - thank you! I'll do some digging to see how much MM I will need for our 28k gallon pool.

Update: I read your test link again, and all the info is there. It says leave pH 7.5 or higher, so maybe I won't touch it for now til after MM?
 

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