Struggling with stains

[UCFKnights]

A couple years ago, I bought a place out of foreclosure with a pool that was neglected for years... when I bought it, the pool was a total swamp, with frogs, tadpoles, and lots of other stuff growing in it, worse then anything I've seen. I knew you weren't supposed to drain the pool as with the inground concrete plaster pools they can pop out of the ground, and I wanted to get it cleaned up ASAP, so I went over there right after I got it at auction, before it had power or anything, and figured i should start shocking the pool as it probably wasn't going to be a fast process killing everything in it and getting it cleaned up, so I wanted the chemicals to start working. There was no testing the water with how dirty it was, so I threw in a bunch of tri-chlor tablets in, and then went the next day and bought a 100 lb bucket of cal hypo to start shocking with that (while it still didn't have power, thus no circulation or filters yet) and also used a few algaecides (for black algae and mustard algae). After a week or so I got the pump running, replaced the filter with a DE one, etc... And after probably a month or 2 after the filter was going, the pool was cleaned up, minus very severe staining.

I kept trying to keep it shocked and brushing the walls (with both wire brush and nylon) twice a day for a few months, and it didn't help. Actually, the stains did disappear in certain areas: the exact spots where I originally through the tri-chlor tablets, the marcite actually completely cleaned up and looks new again, but everywhere else it looks pretty bad. I tried taking the same tablets that appeared to clear it up in a few spots around the pool and rubbed them on the other surfaces, no luck. I've left large amounts of cal hypo granules on them, no fading, nothing. I tried repeating that task of leaving a tablet on other spots, and that didn't fade it either.

I got fustrated, and my problems were now limited to an appearance one, so I figured I'd just leave it and see if the sun would fade it, but a couple years later, it hasn't.

The pool water is crystal clear and has been so for a long time now. The pool seems to be very prone to algae (mustard and black) if I ever let the chlorine levels get low, much faster then any pool I've ever had before, but as long as I keep the FC up, it doesn't show at all, and on the overnight chlorine test, it uses almost nothing. The only other problem of note is this pool seems to get black water rings on the tile much faster then any other pool I have and they don't come off with the nylon brush, but they do come off with a magic eraser really easy, but start to reappear after only a week or 2.

I haven't tried any of the stain remover products other then pumice stones which also did nothing. What would you all recommend or is the pool stained so long/badly that it will be like that forever?

 

[Texas Splash]

Hello and welcome! Don't worry too much about that scum ring around the waterline. It's fairly common. Just hit it with a brush, the Magic Eraser or whatever you have. As for the stains, no doubt you had organic staining from the pre-purchase days when it just sat there. The perfect circles where tabs landed are evidence of that. So here are your stain options:
- Chlorine tabs confirm organic
- Crushed vitamin c tablets in a sock or nylon confirm iron
- Dry acid confirms copper
- If still in doubt... you can order products online like Magic Jack's Stain ID kit that may help.

But we also need to know more about your pool. Please update your signature with all of the pool and equipment info like mine below. Very important - what test kit are you using to the test the water? That is priority #1 for us to help. SO let us know how it goes.

 

[UCFKnights]

I'll have to give the vitamin C thing a try and if not the Magic Stain Stain ID... I'm struggling a bit with why when I threw them in initially it cleared up an area but I can't repeat it now...

My pool is marcite/plaster in ground, 2 hp pump, I'd guess around 20,000 gallons but I gotta remeasure to check, and I use the Taylor K-2005 test kit. I use distilled water to dilute half way on the DPD chlorine test to test up to 10 (although I see on here its recommended I get the powder DPD chlorine test instead which I'll probably do for my next refill which is coming up anyways. I generally use a combination of tri-chlor and hypocal to chlorinate the pool... if the CYA is below my maximum of 50 AND the pool needs acid, I will use tri tablets, if either of those is not true, I treat with hypocal and acid/baking soda/soda ash. I usually test about every other day for pH/Cl and every other week what my CYA/CH/TA is... never have tested anything else. I have used algaecides in the past... probably last time was during Hurricane Irma though, generally I don't need them.

Is it worth buying the phosphate test? Or borate? Would reducing phosphates or add borates help with either the scum line or the stain or is that generally a waste of time?

 

[Texas Splash]

It's possible the tabs worked before simply because they sat for so long in one spot. Those stains could really be ingrained into the plaster. For the test kit, since you have the 2005, all you need is the FAS/DPD Chlorine CC's test and it essentially becomes a 2006 kit. I'd recommend chlorinating with regular bleach. Regular the key word - NO splashless, scented, or fabric (polymer) bleaches. It works well, quickly, and has no side effects like tri-chlor or cal-hypo. No need to test for anything else other than FC, CC, CYA, PH, TA, CH. And refrain from adding any other products tot he water like algicides and stuff. Many of those add other byproducts you can't remove unless you change water.