# Thread: White buildup at filter's air release valve

1. ## White buildup at filter's air release valve

At the top of my Hayward filter, I'm starting to see some crusty white buildup. See attached pic. Is this indicative of any chemistry problem I should be paying attention to?

I've been living in this house for six years and haven't seen anything like that in six years.

Imgur: The most awesome images on the Internet

2. ## Re: White buildup at filter's air release valve

Could be scale. Use PoolMath to calculate your CSI and keep it between -0.3 and 0 to avoid scale. More here, Pool School - Calcium Scaling

Just FYI many can't won't or don't click out of the site to view pics. Myself included, I read hundreds of posts per day and it would significantly reduce the number of posts I could read and respond to. Photobucket allows you to copy IMG code and paste it in your post to embed the pic in the thread. I don't know if your photo host offers this feature.

3. ## Re: White buildup at filter's air release valve

Thanks!

Imgur used to, but I didn't see that option today. Will try Photobucket in the future.

Thanks,

5. ## Re: White buildup at filter's air release valve

Helpful to identifying the buildup (it is probably calcium) would be to post a complete set of test results......do you test your pool water?

6. ## Re: White buildup at filter's air release valve

Yes. Tested this morning:

FC = 5
pH = 7.4
TA = 80
Calcium = >400 (too high to get a meaningful reading, but very high)
CYA = 60

I just plugged that into PoolMath. Assuming I used it right (which is a big if), my CSI is -0.13.

7. ## Re: White buildup at filter's air release valve

Well, that Calcium is probably the culprit. At some point in time, your pH has probably also been a bit high but high CH alone is enough to account for what you are seeing.

A solution of muriatic acid mixed with water (3water - 1 muriatic) will clean it off.

8. ## Re: White buildup at filter's air release valve

Thanks, will do!

My pH constantly drifts upwards. I put muriatic acid in the pool usually 3x a week to keep it within range. It has definitely gone above 8.0 occasionally if I miss a few days.

9. ## Re: White buildup at filter's air release valve

That is what is contributing to the scaling. Keep adding acid to lower PH when it gets to 7.8 or 8.0. This will lower your TA over time. Once your TA gets down toward 60 or 50 the PH rise should slow down. You need to get an accurate result on your CH to get a good CSI number. More here on testing it, Pool School - Calcium Hardness

Also, if you have waterfalls or water features run them less, the aeration also raises PH.

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