Calcium leaching from grout.

[DennyB65]

I am continually having to use acid in a spray bottle and a tile stone to get rid of calcium build up coming from the grout in between the glass block of my spillover. Is there something that I can do preventatively to stop this from occuring? Thanks!

[waterbear]

first thing to do would be to post your numbers for pH, TA, CH, surface finish and size of your pool/spa so we can get a handle on whether the problem is from the grout or maybe from your water balance.

[DennyB65]

Sorry, here are the numbers, relatively normal as is usual for my pool. I am very anal about it, I test every other day and add acid as needed to keep the ph around 7.4. Todays results are as follows...........
fc 2.3
ph 7.5
ta 95
ch 330
stab 78

Thanks in advance waterbear.

[duraleigh]

Hi, Denny,

Two thoughts looking at your posts.

You said you add acid to keep your pH around 7.4. Does it rise pretty much on it's own? If so, do you think it has ever slipped up a little too high? If its gotten up around 8 or so, that is probably enough to cause some scaling.

Secondly, I don't understand your FC and CYA results. FC should be in whole numbers and CYA typically is not defineable in less than increments of 10...10, 20, etc.

I know that your question was about scaling but you'll probably need to run your FC up around 6-9ppm with a CYA of 80 for it to be effective.

Dave S.

[waterbear]

Hi, Denny,

Two thoughts looking at your posts.

You said you add acid to keep your pH around 7.4. Does it rise pretty much on it's own? If so, do you think it has ever slipped up a little too high? If its gotten up around 8 or so, that is probably enough to cause some scaling.

Secondly, I don't understand your FC and CYA results. FC should be in whole numbers and CYA typically is not defineable in less than increments of 10...10, 20, etc.
Not necessarily, These sound like pool store numbers and if they are from a testing setup that uses a colorimeter such as the LaMotte Waterlink it is very possible for the meter to read differences in color or turbidity that the human eye cannot distinguish. The accuracy of these numbers would depend on how accurately the meter is calibrated. Drop based test kits are excellent but if you want to spend the money on instrumentation it IS possible to get more accurate results. Colorimeters and turbidity meters are standard laboratory equipment. Using a colorimeter to read a wet cell (such as a DPD test) is going to be much more accurate than comparing the colors on a comparator block with the human eye.

I know that your question was about scaling but you'll probably need to run your FC up around 6-9ppm with a CYA of 80 for it to be effective.

Dave S.

One other thought...might you have a SWG in the system? If so it might not be scale at all but salt deposits from evaporation.

[PoolDoc]

Hi All

Good catch, Duraleigh, on the bogus numbers. More and more pH meters are being sold without buffered calibration solutions OR any explanation of why calibration is essential. We can expect to see more and more off-the-wall pH results, as people use pH meters. The meters will usually (if they aren't made by Hanna) be accurate out of the box, but will drift over time.

However, given the "78" for CYA, I'm suspicious of just where those numbers came from. Denny indicated he tested the pool himself, but unless he's got a photometer (Palintest is selling one) it's unlikely he generated that number himself.

So, like you, I'm left wondering where they came from.

Waterbear . . . acid doesn't dissolve salt. The water in it might . . . but if that were the case, so would the pool water. One general rule: if acid makes it fizz, then it's calcium carbonate deposits. In some parts of the country (eg. AZ), pool owners will have problems with calcium or magnesium sulfate deposits, but it's generally pretty rare. Also, it is common for calcium carbonate laden water to migrate through grout and/or concrete, and deposit stalagtite-like drips and runs. The acid-fizz test will ID those. Also, I have heard of silica deposits being an issue, but I've never confirmed that, or gotten more info on it.

Also, while I'm pretty confident that spectrophotometers from Hach, et. al. are accurate and reliable, I have no such confidence in the low end equipment used in pool stores. My own experience with some of those units has not been positive. Many of these are sold without any calibration process, and even where there is a process, there's no guarantee that it's been followed. It's important to remember that bad testing actually improves pool store profits, so from their point of view, there's no benefit to accuracy.

Ben
PoolDoc