Ring around the pool floor

[Jimjones666]

I have a ring around the pool floor it has been there for years. Recently have decided to attack it, tested it with a vit C tablet but nothing thinking it was mustard algae have been scrubbing it hard 2-3 times a day for 3 days with pool brush and have increased the chlorine to 3-4 Liters at night for 3 nights... nothing. Got angry and added strong Cu algecide .... nothing. except a stain which I had to remove with citric acid.
I previously used granular chlorine and the calcium hardness is off the charts, but have switched to liquid now for the last month or so.

Last test results just before the extra chlorine-
FC- 3
CC- 0.07
PH - 7.2
CYA - 27
TA - 92
Cu - 0.3

I have attached pictures if anyone has any ideas.
Any help would be appreciated.

 

[Texas Splash]

Welcome to TFP! Do you have your CH level handy? Can you confirm who tested the water to get those results? Also take a moment to update your signature with all of your pool and equipment info. It will help with each post. Thanks for posting.

 

[Jimjones666]

@Texas Splash thanks for replying.
The CH is 1100. (was told because of using granular chlorine)
The test was done by a pool shop with some fancy computer and I also tested myself with a basic test kit (could not test everything).

 

[Texas Splash]

Thanks for the update. Unfortunately, a CH of 1100 is a bit too high to manage. I suspect that tarnished-looking rind you see may be calcium staining. There could also be some organic staining mixed in with it as well. If that CH test is accurate, there's no doubt you'll need to exchange some water which is the only good way to lower CH. It would ideal to lower the CH to about 400-500 if possible which would equate to changing about 50-60% of your water. In addition, stop using any powdered cal-hypo (calcium) products. Find a place that sells only liquid chlorine which contains no such CH (or CYA) side effects. Regular laundry each can also be used as long as it is not splashless or scented. @AUSpool and/or @Aussie2020 might hop online and be able to give you some good local vendor options.

Now I'll also say that here at TFP we always recommend owner testing with the proper test kit. In your region, Clear Choice seems to be the best option. Please go to the link below and slide down to "Clear Choice Labs - Australia" for direct links to obtain the equivalent of the Taylor K-206C test kit. Home testing is easy and often more accurate.

Pool Test Kits - Further Reading

www.troublefreepool.com

 

[Jimjones666]

Appreciate your replying Texas Splash, once the CH is normal again will the calcium staining go away over time or is there any way to treat it? Would adding Citric Acid stain remover fix the problem? (once CH is down). I have already stopped using granular chlorine and am now using liquid. I will stop shocking the pool as I think it is just a waste of chlorine as the problem doesn't seem to be algae.
Unfortunately the good test kits here where I live are 3.5 times the cost of the TF-100 that you sell, which I would have purchased if I could have. They are the same cost if not more expensive than an average pool pump and not in my budget at the moment..... Edit- just looked at your link to the Australian kit - alot cheaper than anywhere else I looked for the Taylor, so thanks for that.

 

[Texas Splash]

It's hard to know for certain if the ring will completely go away on it's own. Once the CH is lowered, you will be able to better manage your "CSI" (see the PoolMath APP) to keep it in the slightly negative range (with lots of brushing) which might help the more aggressive water breakdown the ring. That is if it is indeed calcium. Citric acid, or Vitamin C, works on iron staining. I doubt that's it, but you can try rubbing some on a stained area. You can also try rubbing a chlorine tab on the stain to see if there is any organic material in it.

 

[AUSpool]

Geday Jim, and welcome to the forum.

It is often not worth going out of your way trying to save a few cents on the cost of chlorine in Aust. The best is the 20L drums from Bunnings but most LPS store chlorine in bulk and will refill your container for close to the same price, just avoid all their other stuff that you don’t need. For long term FC management you cant go past a salt water chlorinator, just something to think about.

The pool stores do have fancy computer test equipment but that doesn’t guarantee accuracy. The common 4 or 5 way kit is just ok in lew of nothing but it doesn’t have the FAS/DPD FC or CYA tests that are so important. The best option for us in Australia is the gear from Clear Choice.

As for your stain I would only be guessing but it looks like it could be an organic stain as if the the pool was left empty for a while with stagnate water at that level. A pause in refilling after refinishing could produce something like that too. I would try a SLAM Process before summer but with all options exhausted you may be left with refinishing it or just live with it.

 

[scdaren]

Does that ring go all the way around the pool at a level depth (ie same distance from the surface)? If so, I would lean toward it being an organic stain from the pool left partially filled with lots of algae for an extended period of time.

 

[Jimjones666]

Yes the ring goes all the way around the pool but is stronger in the shaded areas, the pool has never been at that low level since it was installed decades ago. I am thinking that Texas Splash is correct and the ring is calcium staining mixed with organic staining and will be taking his advice and see what happens over time.

@AUSpool thanks for the info, when I switched to Liquid I did a lot of shopping around and our local pool stores liquid chlorine is slightly stronger than bunnings in g/L and is also cheaper per Liter, we also get the 10th one free. I would suggest you shop around your local stores to check if you are getting the best deal.

Thanks for all reply's I hope over time the stain will go with brushing and lower CH.