White residue on salt water chlorinator cell

[cdysthe]

Hi,

This is my first post here. I am also new to salt water pools, so bear with me please.

I have a 20K gallon salt water pool. The water is currently balanced and crystal clear and everything seems to work except for one problem: I am having this buildup of white residue on the salt chlorinator cell. The housing is clear so I can see the cell. Some of it is clumps I can peel off while some is a layer on the cell itself that only is removed by soaking the cell in vinegar for an hour. I could live with this if I had to clean it once a week or so, but new buildup happens every day so I have to clean the cell every day. That can't be right. Yes, the water here in South Central Texas (USA) is very hard, but I didn't have this problems as extreme as this before. I have also noticed that the buildup only happens on the top of the cell, the side of the cell facing up. Even if I turn it the buildup is on top. I'm pretty sure it's calcium buildup, but why so much and is there a way I can prevent having to clean the cell daily?

[BigTallGuy]

Hi and welcome to the Forum. You are indeed seeing calcium build up. I agree that cleaning your Salt Cell every day is nonsense. What is the make and model of your SWCG? In any case, Muriatic acid works very well to clean the calcium off of your Cell. I usually mix about a cup of Muriatic Acid to a gallon of water and let the cell soak in a plastic bucket. I would not submurge the electrical contact points, only the plates where the build-up is. It should bubble quite a bit, but after the bubbling stops, there should only be a few small spots left that you can scrape off with a plastic or wooden tool, then rinse. Some cells are self cleaning, at least to a point, and all cells will build up with calcium, some sooner than others. Even if your cell is not of the self cleaning variety, you do not need to clean it daily, probably not even weekly. Your cell, if it is rated big enough for your pool, should be able to keep up with your chlorine demand even with some calcium build up.

[PoolDoc]

The water is currently balanced and crystal clear

How do you know this? If you are using test strips, or trusting dealer testing . . . you do NOT know that this is so. There are some dealers with accurate testing, but they are the exception, not the rule. And 'guess-strips' are, well, 'guess strips'!

Read the test kit info page in my signature; buy an HTH 6-way drops kit from Walmart, if it happens to be available in your area.

[cdysthe]

How do you know this? If you are using test strips, or trusting dealer testing . . . you do NOT know that this is so. There are some dealers with accurate testing, but they are the exception, not the rule. And 'guess-strips' are, well, 'guess strips'!

Read the test kit info page in my signature; buy an HTH 6-way drops kit from Walmart, if it happens to be available in your area.

Well, I know it's crystal clear since I can see that it is. I use a PentairPro II Test Lab to test the water and double check with the pool store now and then. Calcium hardness will always be on the high side here since the water is very hard. It's also hot and windy around here so I'm seeing a lot of evaporation during summer and have to refill with hard water

[cdysthe]

Hi and welcome to the Forum. You are indeed seeing calcium build up. I agree that cleaning your Salt Cell every day is nonsense. What is the make and model of your SWCG? In any case, Muriatic acid works very well to clean the calcium off of your Cell. I usually mix about a cup of Muriatic Acid to a gallon of water and let the cell soak in a plastic bucket. I would not submerge the electrical contact points, only the plates where the build-up is. It should bubble quite a bit, but after the bubbling stops, there should only be a few small spots left that you can scrape off with a plastic or wooden tool, then rinse. Some cells are self cleaning, at least to a point, and all cells will build up with calcium, some sooner than others. Even if your cell is not of the self cleaning variety, you do not need to clean it daily, probably not even weekly. Your cell, if it is rated big enough for your pool, should be able to keep up with your chlorine demand even with some calcium build up.

Thank you. I've got at Hayward Aquarite 25k Gallon Turbo Cell. I do not think I can leave the cell for as long as you suggest with the current water. It's simply too much build-up. As I said in another response in this thread the water here is very hard, nothing I can do about that. I've seen some products which claims to "protect" the salt cell and "prevent" or "limit" buildup. Would it be worth the cost trying on of those? I will also try to clean the cell with diluted muriatic acid instead of vinegar. Thank you for that advice.

[PoolDoc]

I use a PentairPro II Test Lab to test the water and double check with the pool store now and then.

Ok, had to look it up. It's the old Rainbow kit. It should be better than strips, but I have no idea beyond that whether it's reliable or not. Because it's DPD tablets for chlorine, you can only test chlorine to FC or TC=5 ppm, and not very accurately at that. Also, because you just said "it's balanced and clear" without numbers, I needed to figure out what you were going by. It sounds like your following the test kit guide? We've never seen one of those (even the Taylor booklet) that was right.

So, do this:

1. Post your pool info to the chart (abt 30 seconds) so we have a clear picture of what you're working with

Pool Chart Entry Form (http://goo.gl/cNPUO)
Pool Chart Results (http://goo.gl/PXaLu)

2. Post your actual test results, for BOTH pool water and FILL water. (You only need to test pH, TA, and hardness on fill water)


For now, I'd turn off the cell, and chlorinate by hand.

[cdysthe]

Thanks again. I posted the pool data form as 'cdysthe'

The pool water:
Free Chlorine: 1.2 ppm
Total Chlorine: 1.2 ppm
PH 7.2
Hardness 350 ppm
TA 120
Cyanuric Acid 50 ppm


Fill water:
PH 7,2
TA: 340 ppm
Hardness: 350 ppm

[PoolDoc]

Hi CD;

Sorry about the question about clarity -- didn't mean to ask that. Just when someone tells us the water is balanced, without numbers, we've learned it usually isn't.

OK, you've got some hard fill water. If those numbers are correct (remember, I don't trust the Rainbow kit -- it may be OK, but I don't know) AND if the AquaRite is working properly, you shouldn't be picking up scale. Let's do this:

1. Chlorinate manually for now. An easy way to do it is with undiluted dichlor
==> Sams Club "PoolBrand" 24lb box of dichlor shock - EXCELLENT price, if available. Otherwise
==> Kem-Tek Dichlor 22 lbs (http://www.amazon.com/exec/obidos/ASIN/B0030BEHZA/poolbooks) @ Amazon
(Almost all other locally available brands are diluted or mixed with goo.)

2. Raise your CYA to the recommended 80 ppm (if you use dichlor, you'll do both)

3. Clean your SWCG cell, per Hayward's AquaRite manual (www.hayward-pool.com/pdf/manuals/Manual345.pdf), pgs 8 & 9 (page order screwed up!):

Servicing and Cleaning the Aqua Rite cell
Turn off power to the Aqua Rite before removing the electrolytic cell. Once removed, look inside the cell and inspect for scale formation (light colored crusty or flaky deposits) on the plates and for any debris which has passed through the filter and caught on the plates. If no deposits are visible, reinstall. If deposits are seen, use a high pressure garden hose and try to flush the scale off. If this is not successful, use a plastic or wood
tool (do not use metal as this will scratch the coating off the plates) and scrape deposits off of plates. Note that a buildup on the cell indicates that there is an unusually high calcium level in the pool (old pool water is usually the cause). If this is not corrected,
you may to have to periodically clean the cell. The simplest way to avoid this is to bring the pool chemistry to the recommended levels as specified.

Mild Acid Washing: Use only in severe cases where flushing and scraping will not remove the majority of deposits. To acid wash, turn off power to Aqua Rite. Remove cell from piping. In a clean plastic container, mix a 4:1 solution of water to muriatic acid (one gallon of water to one quart of muriatic acid). ALWAYS ADD ACID TO WATER - NEVER ADD WATER TO ACID. Be sure to wear rubber gloves and appropriate eye protection. The level of the solution in the container should just reach the top of the cell so that the wire harness compartment is NOT submerged. It may be helpful to coil the wiring before immersing the cell. The cell should soak for a few minutes and then rinse with a high pressure garden hose. If any deposits are still visible, repeat soaking and
rinsing. Replace cell and inspect again periodically.

4. Lower your alkalinity to 60 - 80 ppm (fine for vinyl pool): Lowering your Alkalinity Step by Step (http://www.poolsolutions.com/gd/lowering-swimming-pool-alkalinity-step-by-step.html)

5. Once your CYA> 75 ppm, your pool is algae free, and your TA < 80 ppm, turn your SWCG back on.

6. Re-inspect after a week, for scale. If there's no scale, simply continue, and maintain these conditions. Shock with bleach, when you need chlorine but no CYA; shock with dichlor, when your CYA is drifting down.

7. Maintain pH with muriatic acid (lowers) and 20 Mule Team Borax (raises). Do NOT use baking soda or washing soda (pH UP)

If this fails, we'll have to get fancy. But if this works, it's cheap and stable, and won't create other issues to watch out for.

[cdysthe]

If this fails, we'll have to get fancy. But if this works, it's cheap and stable, and won't create other issues to watch out for.

Got some work to do. Off to Sam's this morning for shock. Otherwise I stop by the pool store and have the fill water tested making sure my data is correct. The pool water data I submitted was actually from the pool store which corresponded nearly perfectly with my own numbers. I will get back here and report progress (or lack of such) in a week.

I've learned now that I should always submit water data before asking. As for asking about the water being clear, no problem, it made go back out there and look one more time! :)

Thank you so much!

[cdysthe]

Just one quick question, you say shock with bleach. Do you mean household bleach?

[PoolDoc]

Plain 6% household bleach. Walmart store brand is preferred to Clorox, because with Clorox there's the chance of getting one of their gooped-up products, that's not suitable for pools.

[cdysthe]

Last question in this regard. I have been using this product for shocking and have some left:

SMART Chlorinating Solution: http://www.sunbeltchemicals.com/details/sunbelt_brands.php

Can I use this product for shocking now until it's used?

[PoolDoc]

It's just 10% bleach; it should be fine.

[cdysthe]

I've been adding a little acid per day and TA is down to 100, but another strange thing is happening. The sand filter (zeo sand) had gotten clogged up twice to the extent I had to backwash. When I backwashed what came out looked like skim milk, not the normal brownish looking stuff I normally see. What could cause this?

[aylad]

My guess would be calcium that is now dissolving since your pH and alk are lower.

[PoolDoc]

The sand filter (zeo sand) had gotten clogged up twice to the extent I had to backwash. When I backwashed what came out looked like skim milk, not the normal brownish looking stuff I normally see.

Are you adding the bleach via the skimmer? If so, my guess is you may be precipitating calcium carbonate, and then trapping it on the filter. This is a GOOD thing.

Another way to check is to catch a bucket full of the backwash, and let it settle overnight. Pour off most of the water. Take a tablespoon of the white goop, and put it in a glass measuring cup. Add 1/2 cup of vinegar. If it bubbles -- it's at least partly calcium carbonate.

[cdysthe]

Are you adding the bleach via the skimmer? If so, my guess is you may be precipitating calcium carbonate, and then trapping it on the filter. This is a GOOD thing.

Another way to check is to catch a bucket full of the backwash, and let it settle overnight. Pour off most of the water. Take a tablespoon of the white goop, and put it in a glass measuring cup. Add 1/2 cup of vinegar. If it bubbles -- it's at least partly calcium carbonate.

Yes, I have added the bleach to the skimmer since it's vinyl pool and I'm afraid of damage. I add it slowly thought for minimal damage to filter and pump. I did gather backwash last night and tested the goop with vinegar today. It bubbles. TA is now at 80 so I put the salt cell back in action, and guess what, no white residiue! PH is currently 7.0, but is rising because of evaporation and refill (Texas sun!). Thank you so much for all the advice. And btw, the water feels much nicer now also according to the kids who are able to sense every little difference in water quality simply because they are in there for hours every day. The best baby sitter ever! :)

[aylad]

The best baby sitter ever! :)

That's an understatement!!! :D

Janet

[cdysthe]

That's an understatement!!! :D

Janet

There were some errors in my previous post: The TA is now at 80, it says "not at 80". I can't find how to edit my post on this forum. Is it disabled?

[Watermom]

I fixed it for you. I'm not sure if editing is disabled or not. If there is not an 'edit post' button on the lower right section (beside the 'reply' button,) then it must be disabled.