Help with Scum Line


Nov 7, 2016
Hi, First year owner. Managing my own chems. I thought I was keeping up on everything over the winter. Recently, as I let the water evaporate down to fix some grout cracks noticed a pretty significant scum line at where the water level normally sits. I used the magic eraser pads and they seem to knock it down pretty good. Will need to hit the grout section with something else though. I have two questions, is there anything in the water chemistry that I can do to help with the scum line now? Second question, what do I need to do differently in my maintenance to prevent this in the future?

I have always had to struggle with maintaining the pH this last year. Wants to drift on me. I don't think I let it go beyond 7.8, but it did tend to rise to that level often. Only other parameter I missed on this year was chlorine. I use liquid chlorine and once the temperature turned to colder I under estimated how little the chlorine leaves the pool. Using my normal application up through October it spikes to over 10 ppm, maybe as high as 20. Took about 3 months and a lot of rain for it to come down to a normal reading. Kept the algae away at least.

What did I do wrong and is it best correct? Thanks in advance.

I use a Taylor K-2006 kit

FC 4.5
CC 0
PH 7.4
TA 80
CH 160
CYA 45


Mod Squad
TFP Expert
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In The Industry
Apr 1, 2007
Sebring, Florida
You have a very nice concept of what we teach. I don't think you did anything wrong.

1. Try some 2:1 water/muriatic acid on that scum line AFTER you clean it first with 409 on an abrasive pad. The 409 will get the dirt and grime and then the acid will get the calcium.

2. If you find out that you had quite a bit of calcium, work harder on a lower pH and it should minimize it

Lastly, you mauy not have any calcium at all and the 409 will take it off (don't get your hopes up, but maybe! Be sure to rinse the water/acid from the grout

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