Scale/calcium at water line - unavoidable?

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R

Rootyb

0
Feb 24, 2015
65
Davis, CA
Long story short: we had new pebble-tec installed a year ago. Since the fall, we've had a guy taking care of the pool. We've had some algae over the winter (not bad, but some on the tile/grout mostly). Today, I noticed a pretty major calcium line. It turns out auto-fill was off, too. Is this just kinda something that happens? Did the auto fill being off contribute?

Is this just something that happens? Anything we can do to avoid it in the future?
 
I doubt it. Your chemical balance and combination of source water did it. Many of us have hard water, but we adjust our chemical levels to protect from such things. This is one very big reason we ask pool owners to take the leap, get their own test kit (i.e. TF-100 link below) and take charge of their own pool. You can bet that with YOUR own testing, YOU will be sure of what you have in the water and how to control it. It's a lot easier than you might think. Please consider getting your own TF-100 and post for us a full set of test numbers. The sooner you do the sooner there's a chance you might be able to reverse that trend. I hope you give it some consideration. Have a great weekend.
 
Hey Rootyb,

You've been a forum member since last year so hopefully you've gotten to know that we're pretty much advocates of a do-it-yourself approach to pool water chemistry and maintenance. Sounds to me like your pool-guy wasn't doing much or maybe too much....hard to know without any test results. If he was using cal-hypo shock a lot, then he may have loaded your water up with calcium. Typically a thick water-line calcium scale is indicative of major chemistry imbalance. Considering you've also reported algae growth during the cold winter months (when algae reproduction rates are so low that they become insignificant), it sounds to me like your pool-guy did a lousy job of keeping your pool clean.

Our advice comes with a string attached - you have to get your own test kit (one of the ones we recommend on the forum here), test your water yourself and post results. You can even take a picture of the scaling you are seeing and attach that to your post as well. Then, you will find that we are happy to reply with suggestions.

As for the auto-fill, well, allowing water to continuously evaporate off and then re-fill can leave a calcium stain which is why it is better to leave an autofill on so that the water level does not drastically change. But your water-line calcium scale sounds more excessive than that. Post results and we'll be happy to help.

Good luck,

Matt
 
I had a calcium line developing along my tile a few years ago. With proper management of PH and TA the line is gone and hasn't come back since. But, as mentioned you have to have a good test kit and you have to test and manage your water chemistry. I have used the TF100 from TFTestkits.net for many years. Get a test kit and post some test results and we can help.

Start here for the basics, Pool School - ABCs of Pool Water Chemistry

As for your calcium build up, you can read this now or later after you have a better understanding of your pool, or both! After you test your water input the results into Poolmath, including the temp. It will calculate the CSI score of your water. This tells you the potential for your water to scale. Keep your CSI -0.1 to -0.2 to prevent scaling in your pool. You can keep it -0.3 to -0.5 for a while and brush often to see if you can reduce the scale you have now. This could take all summer. Doing this will make your plaster last years longer. If you have a saltwater chlorine generator it is good for that too. In Poolmath tweak your PH and your TA to adjust the CSI score.

More here
Pool School - Calcium Scaling

and here
Langelier and Calcite Saturation Indices (LSI and CSI)
 
Thanks, all! That's kind of what I figured. We really like our pool guy, but it definitely sounds like he wasn't doing a great job. The convenience is really nice, but with a brand new surface on our pool, I don't want to take chances long-term.

I was doing chemicals myself before we hired him. I know it's not tough. It's just kind of a hassle. Guess I'll just have to get used to spending the time to do it myself.

Bleh. Oh well.


Thanks, everyone! You're always great.
 
Regarding removing the scale, when I mentioned it to our guy, he said he'd bring out some biodex 300 to take it off. Good idea? Bad idea?

Here's a pic (I have no idea how I didn't notice it before yesterday).

CEqWwy1.jpg
 
The MSDS list Biodex 300 as having
3 COMPOSITION/INFORMATION ON INGREDIENTS
Cas # | Percentage | Chemical Name
-------------------------------------------------------------------------------------------------------
N/A | >87% | Proprietary, non-hazardous, non-regulated
7647-01-0 | <5% | Hydrochloric acid
7664-38-2 | <3% | Phosphoric acid
7664-39-3 | <3% | Hydrofluoric acid
N/A | <2% | Trade Secret*
*The specific chemical identities of the ingredients of this mixture labeled as "Trade Secret" are
considered to be proprietary and are withheld in accordance with the provisions of 29CFR1910.1200 Sect.
(i) Trade Secrets.
Click to expand...
So it seems to be nothing more than about 13% acid. The mystery 87% is probably some cornstrach or gelatin substance to thicken it and let it stick.

A cheap spray bottle (empty windex or similar) and some 1:4 Muriatic Acid is a lot cheaper, plus you'll know exactly what you're adding to your pool water. Rubber gloves and a nylon scrubber and some acid and it's gone. Tough stuff can be ground off with a pumice stone. Sounds awful but doesn't destroy tiles. Will leave piles of pumice dust in the pool for you to vacuum.

In the future, keep the pH in range and watch the CSI if you have a lot of Calcium in the water. My CH runs 800-1000 and I don't have a ring around my pool.
 
Good to know. I think I've got some muriatic acid. Might give it a try today.

Also, I went out and tested:
FC: 2.5
CC: 0
Ph: 7.4
TA: 40
CH: 250

I'm out of CYA reagent, or I'd have tested that, too.

Looking at pool calc (with some made up CYA numbers), my CSI looks like it's in the negatives which... Shouldn't that be the opposite of what causes scale?
 
Well that's only a snapshot of your water today; no telling where it was previously. The CSI controls what happens under the water's surface. At the edge, where the water meets the tile, you can get evaporite deposits especially since you said the auto fill was off and the pool level was allowed to evaporate down.

Going forward, if you clean the scale off and keep your CSI a little negative, it should not return. CSI just tells you if scale or etching is possible, it tells you nothing about the rate at which it will happen.
 
Roger that.

Also, I noticed some small rust stains last week (a piece of wire ended up in the pool and sat on the bottom long enough to leave a few spots). I mentioned it to our pool guy, and he said he added something to the water to help. It didn't, and I'm gonna try ascorbic acid, but could whatever he added have contributed to the scale?
 

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