Seeking Advice on Calcium Build Up

[Rover]

I have a noticeable, hard calcium build up along my trim tiles. I've used a descaler spray but to no avail. Not sure if I should seek professional help (bead blasting) or tackle this on my own. I need a powerful descaler and would prefer not to directly handle muriatic acid (MA)--the scent reminds me of death! Can somebody recommend an excellent descaler for the tiles?

Also, I noticed that there are some scaling (or what I think it is) inside the spa, specifically around the edges of the seat and the steps. Can I remove the scaling using a pumice stone or is there a chemical additive that I need to apply? It seems like scaling inside the pool is more prevalent in the spa than in the pool. In this case, can I introduce MA in the spa and jst have the water with MA re-circulate only in the spa so I can tackle the build up? Is this safe? Or is it time for me to seek professional help?

I appreciate any advice you can give me and I thank you in advance.

 

[BoDarville]

Rover:

Welcome to TFP

I had the same calcium ring around the tile in both the pool and the spa when I purchased this house. Upon discovering TFP and learning how to properly manage pool water chemistry, the ring has disappeared from the pool and is fading fast in the spa. The key is managing pH and TA and avoiding the use of cal-hypo chlorine products. Now, the rings will not disappear overnight - mine took over a year. On the plus side, no elbow grease or harsh chemical treatments were needed.

When you get a chance, can you post test results? This will allow us to help you better.

BTW, here's a post from one of our TFP Experts who has battled scale and extremely high CH for some time. Nevertheless, he has made great progress in reducing calcium scale: http://www.troublefreepool.com/progress-on-scale-t38568.html?hilit=progress on calcium scale

 

[Rover]

BoDarville,

What does CSI stand for as stated in the post you referred me to?

 

[chem geek]

"Calcite Saturation Index". Some call it the "Langelier Saturation Index" or LSI, but Langelier never wanted it to be named after him and it's a basic formula derived from standard formulas so there is nothing special nor unique about it. It just tells you if scaling or dissolving of calcium carbonate is possible. If you enter in your water parameters into The Pool Calculator, then it will calculate the CSI for you.

 

[Rover]

Thanks for the CSI definition. Is it wise for me to pour the right amount of MA in the spa and shutting off the waterfall return to the pool to get the acid to work inside the spa? If I do this while the pump is running for a day or so and scrub the spa while the water is circulating, would I be able to remove the scaling inside the spa easier?

 

[chem geek]

Yes, you can lower the pH in your spa to help remove scale there and can just recirculate the spa separate from the pool if that is an option.

 

[Rover]

One more question: if adding MA just to the spa, could there be potential damage to the pool equipment and/or the surface integrity of the spa?

I'll test my water and post results this weekend.

 

[chem geek]

It's not a problem if you don't lower the pH very low for a long time. Your test kit probably only goes down to 6.8 or 7.0 anyway so just go to the next-to-lowest reading on the test kit and hold the pH there. The pH will tend to rise if there is aeration so you may need to keep adding acid to keep it lower. If the scale is relatively new, it should dissolve back into the water. If it's older, you may need to add a scale removal product, but mostly they are just metal sequestrants such as HEDP that we recommend for preventing metal staining.

 

[Rover]

Thanks for the advice. So, what I'm understanding so far is the following:

* lowering the pH by adding acid will help me get rid of the scaling in the spa.
* lowering the pH for a short period of time should not harm the equipment or the surface of the spa.
* if scaling is persistent, add a scale removal product.

Is there any other thing I should consider and/or know about?

My project for this long Memorial Day weekend is to tackle this job. I will be adding MA into the spa and let water recirculate in the spa only. I will be scrubbing my trim tile both in the spa and pool with a MA/water solution. Hopefully, I can minimize the scaling and continue this process until I remove all the scale.

Right now I'm running my pump for 4 hours each day, should I increase the run time while I'm doing this project?

 

[chem geek]

You've got it. You might bump up the pump runtime during the project if for no other reason to circulate the more acidic water (actually less alkaline since at 7.0 you would be neutral) to help dissolve even when you aren't there scrubbing to help it along.

If the scale isn't dissolving, then you could create a dilute acid solution of one teaspoon of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in one gallon of tap water. This should be a low pH of around 2.1 or so depending on your tap water's starting TA. You could then use a rag to carefully wipe the scale which should bubble and get removed. Just be careful not to wipe the underlying spa material for too long (if you are brief, it should be fine), and then rinse the area with the bulk spa water.

 

[Rover]

One last question (sorry). Is it ok to have the ph down and put the scale remover additive? Or is this not recommended since the water maybe too acidic and could etch the pool and/or damage the heater parts and other pool equipment? Thanks!

 

[chem geek]

That depends on the scale remover additive (i.e. how acidic it is), but I doubt it will lower the pH that much especially if you are already down to around 7.0. You should be OK doing both. Those additives don't lower the pH by that much (i.e. they aren't that strong an acid).

You can roughly gauge the pH even if it's below 7.0 by measuring the TA level before and after. If the TA test turns red right away, then that's a pH of 4.5 or lower and would be much too low, but I'm sure you'll get nowhere near that. If you are starting with 7.5 pH and 80 ppm TA and have 30 ppm CYA in the water, then the TA and pH relationship will be something like the following as you add acid to the water. Each step below represents adding 0.9 fluid ounces of full-strength Muriatic Acid or 1.2 ounces weight (0.8 ounces volume) of dry acid to 350 gallons.

TA ........ pH
80 ........ 7.5
70 ........ 7.0
60 ........ 6.7
50 ........ 6.5
40 ........ 6.3
30 ........ 6.0
20 ........ 5.8
10 ........ 5.4
. 5 ........ 5.1
. 0 ........ 4.5

So you can see that the buffering is rather strong so prevents a pH "crash" unless you add a huge amount of acid. Short-term (i.e. days, not weeks or months) exposure to pH of 6 or 5 isn't going to corrode metal by any noticeable amount.