Is my cell dying?

The other day I started my Aqua Rite SWCG (T-15 cell). The low salt light started flashing (the panel was reading 2600 ppm). I checked the level with the salt test strips and got a level of 2970 ppm, which is in the normal range for my SWCG. I found this odd since last season the strips and the SWCG were within 100 ppm of each other.

I went ahead and added 50# of salt which should raise the salt level by 300 ppm. The next day the SWCG did register a 300 ppm increase and all other readings on the panel were normal, so I started it up again, setting it to 50% like I normally do at the beginning of the season. The next day I checked CL and found it had dropped by 1.5 ppm, just like it had been doing each day before I turned on the SWCG. Now, it had been cloudly and cool all week, then sunny and warmer the day the SWCG ran, so I'm hoping this is the reason for the drop, but I'm concerned the cell may not be generating enough CL. Last night I increased the SWCG to 60% to see if CL stabililzes. I'll check it again this evening and tomorrow to see what happens.

Is it possible that my cell isn't working despite the panel giving normal readings?

For reference, this will be our 6th season on this cell (it was installed in June 2008) and our swim season runs about 5-6 months.

PS - If I do need a new cell, is this one the same as my Aqua Rite T-15 cell?

http://www.amazon.com/Hayward-Goldli...+turbo+cell+15

The pool store wants twice the price for a new cell, so I'm seriously considering ordering online this time (any reason why I shouldn't??).

Have you tried a full on acid wash? Last year I had a similar issue with the aqua rite t-15 reading a little lower than my test kit. I bought a k-1766 because I was doubting the strips. In the end, I cleared it up with an acid wash per the manual.

Did you try cleaning it? Calcium deposit can make it behave the same way.

Also, the T-15 cell is the 40k size.

When my cell gives out, I might try this one: http://www.titaniumcells.com/index.html

Thanks you. I greatly appreciate the suggestions.

When I closed the pool last fall the cell did have some calcium deposits so I did a manual cleaning per manufacture's instructions (sprayed with hose nozel and scraped off with wooden toothpicks). The manufacture only recommends acid washing in severe cases (I didn't think it was anywhere near severe). Btw, since the cell was installed in 2008, this is the first time it had any scaling. There's a thread about that here;

http://www.poolforum.com/pf2/showthr...-on-cell...why

As mentioned in my original post, I increased the SWCG to 60%, there was still a loss, but only .5ppm this time. Just to make sure the cell was generating CL, I ran it at 100% for 10 hours which resulted in an increase of 2 ppm.

So the cell is generating CL. At this point I'm thinking that the cell is OK but the colder than normal water temps (it's been in the low 70s) and perhaps the cell's age mean I just have to run it at a higher setting than I'm use to for now. This morning I set it to 65% and will see if it stabilizes. If I can't get it to stabilize, I'll try an acid wash.

I'll update again later.

PS - Any idea if the cell I linked to in my original post is the same as mine? I'm thinking it is, but am not sure. I thought about a "generic" cell, but I've read a few posts where there were problems with correct salt readings, so I think I'll stick with an OEM cell.

PPS - I just discovered that my Aqua Rite is running software version 1.5, so is compatible with the newer T-3 and T-9 cells. I thought this was strange since it was installed in 2004 (the newer version didn't come out until 2009), but looking at my notes I was reminded that the main board had to be replaced in 2009, hence the updated version. Interesting, but I'll stick with the T-15 cell as it should last longer.

I think that it is, that looks like a genuine Hayward/Goldline cell from what I can tell and the pricing seems about right for genuine parts to me. I was looking at that very one (I'm pretty sure) last year. The off brand cells tend to look a bit different and are $100 or more cheaper than that. Even my local pool store sells the hayward cell for around that price. If you're pool store is selling them for twice that price, my guess is that they're also including the control panel. Either that or they are going to include a free jar of K-Y with it.

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Originally Posted by kelemvor

I think that it is, that looks like a genuine Hayward/Goldline cell from what I can tell and the pricing seems about right for genuine parts to me. I was looking at that very one (I'm pretty sure) last year. The off brand cells tend to look a bit different and are $100 or more cheaper than that. Even my local pool store sells the hayward cell for around that price. If you're pool store is selling them for twice that price, my guess is that they're also including the control panel. Either that or they are going to include a free jar of K-Y with it.

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Thanks. :)

We were talking about when I might need a new cell when he mentioned it would cost $900+. Perhaps he was just mistaken and was talking about the whole system. Whatever the case, I'm not paying that much for a cell (or KY! LOL).

The generic I posted is a little different than other generics like you would see on ebay. This one has a redesigned cell for longer life. The few people that have purchased the titanium are fairly happy with it. Other generic brands I agree, they see to have issues.

Update...

As I mentioned yesterday, I increased the SWCG to 65%. I tested again this evening and the CL level increased by .5 ppm. So the cell is working, although I'm having to set it at a higher level than when it was new. I turned it down slightly to 63% to see if CL levels off.

I know the manual says only to acid wash if scaling is severe, but I'm wondering if an acid wash might help it work more efficiently? I did find one post where their salt reading was incorrectly low and an acid wash corrected the issue. I've never acid washed it before (again, it was installed in June 2008). Might I harm the cell or shorten its life by doing an acid wash?

Definitely, I would try acid cleaning. I am surprised you went this long without an acid clean. That is usually the first thing I do when I detect a decrease in cell output. Manual cleaning only gets the deposits you can see which is basically the ends of the cell. The internals are not easily cleaned manually.

Also, I clean my cell with acid several times during the season and the cell is over 7 years old and still going strong. I don't use full strength (1:4) and just long enough until all the fizzing stops.

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Originally Posted by mas985

Definitely, I would try acid cleaning. I am surprised you went this long without an acid clean. That is usually the first thing I do when I detect a decrease in cell output. Manual cleaning only gets the deposits you can see which is basically the ends of the cell. The internals are not easily cleaned manually.

Also, I clean my cell with acid several times during the season and the cell is over 7 years old and still going strong. I don't use full strength (1:4) and just long enough until all the fizzing stops.

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Thanks. That gives me the confidence to try an acid cleaning. I was hesitant before because the manual had me thinking that acid washing could harm the cell, hence the instruction to only use acid if scaling was "severe".

I do need to order a cleaning stand so I don't have to immerse the cell into a bucket.

So the solution you use is one part muriatic acid with 4 parts water?

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Originally Posted by JimK

So the solution you use is one part muriatic acid with 4 parts water?

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Correct.

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Originally Posted by mas985

Correct.

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Thanks.

How do I safely dispose of the acid solution when I'm done?

Probably the safest place is back in the pool. You would be adding CH back to the pool but it is probably small compared to what is already in the pool. Just keep track of how much acid is in the solution so you don't add back too much at once. Basically your normal dosing. I clean my cell in a dosing bucket so I just use it for dosing at a later time.

Otherwise, you would have to dilute it further and perhaps neutralize it before disposing in a drain.

Remember (9th grade chem) when diluting acid, you put acid into water (A->W). Never water into acid. Wear goggles, gloves, avoid the fumes, have a plan for if it spills.

I'm sure you know all this already, but if not... See Using Muriatic Acid to Safely Lower Your Pool's pH.

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Originally Posted by mas985

Probably the safest place is back in the pool. You would be adding CH back to the pool but it is probably small compared to what is already in the pool. Just keep track of how much acid is in the solution so you don't add back too much at once. Basically your normal dosing. I clean my cell in a dosing bucket so I just use it for dosing at a later time.

Otherwise, you would have to dilute it further and perhaps neutralize it before disposing in a drain.

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Thanks for the tips.

Since I'll be using a cleaning stand and just filling the cell with the acid solution (as apposed to soaking the cell in a bucket), I expect I won't be using that much acid. However, I'd prefer not to add CH back into the pool if possible. I'm hoping to let it drop this year. At closing last year CH was at about 250 ppm. This will be my first season not adding anything with calcium, ie - I use to use Cal Hypo to shock, this year it will be strickly plain bleach to shock when needed.

This will be the first time I've done this, so I'm trying to be prepaired to avoid any unpleasant surprises.

Tips and suggestions are most welcome. :)

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Originally Posted by BigDave

Remember (9th grade chem) when diluting acid, you put acid into water (A->W). Never water into acid. Wear goggles, gloves, avoid the fumes, have a plan for if it spills.

I'm sure you know all this already, but if not... See Using Muriatic Acid to Safely Lower Your Pool's pH.

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Thanks for the tips. :)

Yes, I've read that link (will do so again to refresh my memory) and always put acid into water. I remember seeing a demo on TV where they put a drop of water into acid and the results were quite explosive! :eek:

I know there are strong fumes when pouring the acid, are the fumes still strong once diluted for cell cleaning (4 parts water, 1 part acid)?

I guess I should do this in the yard somewhere. I'm thinking worst case if I accidently spill some of the solution it's just kill a grass spot (much easier to fix than a damaged patio).

For disposal, any idea how much to dilute the solution to make it safe to put down the drain?

Let's see... I don't know but I guess that bringing the solution up to a pH in the 7 - 8 range would be ok. That'll take a lot of water... Do you happen to have alot of water just laying around in your yard?

Seriously though - I'd just do as mas985 suggests and use it in the pool. As I understand most SWCG pools require regular additions of acid to combat pH rise. I doubt the amount of calcium on the plates would even be noticeable in the pool.

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Originally Posted by BigDave

Let's see... I don't know but I guess that bringing the solution up to a pH in the 7 - 8 range would be ok. That'll take a lot of water... Do you happen to have alot of water just laying around in your yard?

Seriously though - I'd just do as mas985 suggests and use it in the pool. As I understand most SWCG pools require regular additions of acid to combat pH rise. I doubt the amount of calcium on the plates would even be noticeable in the pool.

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Thanks.

Sounds like adding it to the pool is going to be the easiest and safest option. Right now my pH has been about 7.4, so I'll have to see how much acid I end up using. I suspect it won't be enough to impact pH by much (don't want it getting too low).

I ordered the cleaning stand yesterday and it should be here this week.

When I'm done with mine, I neutralize it with baking soda then dump it to waste. I figure it's got all the calcium deposits that it cleaned from the cell in that water and I'd prefer not to put it back into the pool.

You don't end up using very much acid at all when using one of the "holders". Only a cup or two if memory serves. You only have to mix up enough to fill the inside of the cell instead of filling a 5 gallon bucket to submerge the cell into.

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Originally Posted by kelemvor

When I'm done with mine, I neutralize it with baking soda then dump it to waste. I figure it's got all the calcium deposits that it cleaned from the cell in that water and I'd prefer not to put it back into the pool.

You don't end up using very much acid at all when using one of the "holders". Only a cup or two if memory serves. You only have to mix up enough to fill the inside of the cell instead of filling a 5 gallon bucket to submerge the cell into.

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I considered doing the same, but it seems there are potential hazards (fuming, heat generated). I'd love to hear the details on how to do it this way (safely) and how much baking soda it takes to neutralize the acid solution.

I just dumped the acid solution back into a small bucket, then added baking soda slowly until there was no more noticeable reaction. Then I added a good bit more, and later dumped it and washed it away. It foams up a good bit when you start adding the soda.

After cleaning up an accidental muriatic spill a month or two before I did the cell cleaning I was significantly less timid about things.

Maybe someone else will have some more scientific details to share on the calculation to neutralize muriatic with baking soda.

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Originally Posted by kelemvor

I just dumped the acid solution back into a small bucket, then added baking soda slowly until there was no more noticeable reaction. Then I added a good bit more, and later dumped it and washed it away. It foams up a good bit when you start adding the soda.

After cleaning up an accidental muriatic spill a month or two before I did the cell cleaning I was significantly less timid about things.

Maybe someone else will have some more scientific details to share on the calculation to neutralize muriatic with baking soda.

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Do you have a general idea of how much baking soda you use? A few cups? Many cups?

Memory's a little fuzzy since it was last fall, but I think it was about 2 lbs (1/2 of one of the "large" boxes of arm and hammer). Since I had that acid spill I keep several boxes on hand at home "just in case".

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Originally Posted by kelemvor

Memory's a little fuzzy since it was last fall, but I think it was about 2 lbs (1/2 of one of the "large" boxes of arm and hammer). Since I had that acid spill I keep several boxes on hand at home "just in case".

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Thanks. I might give that a try the first time and see how it goes.

Like you, I don't want to put the calcium back into the pool, but like was mentioned, it's probably an very insignificant amount. At least I know my options now.

Forgive me but that seems like a lot of trouble for so little CH compared to what is in the pool. 400 ppm CH in a 20 k pool is over 66 lbs. The amount on the cell is probably less than a couple of grams. Close to a 15000:1 ratio. Fill water probably adds more than that in a day.

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Originally Posted by mas985

Forgive me but that seems like a lot of trouble for so little CH compared to what is in the pool. 400 ppm CH in a 20 k pool is over 66 lbs. The amount on the cell is probably less than a couple of grams. Close to a 15000:1 ratio. Fill water probably adds more than that in a day.

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A couple grams is all? Put that way it does seem that putting it in the pool is the easiest thing to do without any real consequence.

I greatly appreciate y'all sharing your experience using both methods. :)

Agreed. I guess I didn't consider how little would be on the cell. Thanks for the tip, mas985.

UPDATE

I cleaned the cell today with the acid solution as recommended (4 parts water, 1 part muriatic acid: 4 cups water and 1 cup acid turned out to be just about the right amount to fill the T 15 cell). There didn't seem to be much bubbling, so I'm guessing there really wasn't much calcium on the cell plates. I checked the controller readings after reinstalling the cell and didn't notice anything different. I'll keep any eye on CL level to see if the cell is working more effectively or not (based on the unchanged controller readings, I suspect not).

I'll post an update once I see if the cell's efficiency has changed or not.

Thanks for all the feedback and help.

PS - Btw, I just dumped the used acid solution back into the pool. ;)

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Originally Posted by JimK

Update...

As I mentioned yesterday, I increased the SWCG to 65%. I tested again this evening and the CL level increased by .5 ppm. So the cell is working, although I'm having to set it at a higher level than when it was new. I turned it down slightly to 63% to see if CL levels off.....

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At 63%, CL was still increasing, so yesterday I dropped it to 55%. It's apparent the cell is still working. Hopefully it won't give out any time soon.

One other thought. There are many "events" which can create excess chlorine demand such as pollen or even not killing all the algae after opening. So that could have accounted for the lower FC levels.

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Originally Posted by mas985

One other thought. There are many "events" which can create excess chlorine demand such as pollen or even not killing all the algae after opening. So that could have accounted for the lower FC levels.

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True. Pollen was really bad this spring.

At opening I did keep CL at shock level until CC was 0 and CL loss stopped dropping much overnight. This year it only took a couple days or so to get there. Previous years took longer and much more CL.

I found it interesting that over this past winter my CYA didn't drop at all, unlike previous winters were it plummeted. I understand the by products of CYA being eaten up create high CL demand. I guess that explains why I didn't need near as much CL at startup this season.

UPDATE:

My cell seems to be having no trouble maintaining CL, so apparently it hasn't given out yet. The only mystery left is why last year the controller's salt reading was the same as my test strips, but this year the controller is reading about 300ppm lower than the strips.

Maybe it's time to try a taylor k-1766 drop based salt test kit? My local pool store actually carries those.

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Originally Posted by kelemvor

Maybe it's time to try a taylor k-1766 drop based salt test kit? My local pool store actually carries those.

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Thanks for the suggestion. :)

I looked into that before and decided to go with the AquaCheck Salt Strips that were recommended here. I was told the strips do a good job (they seem to do fine).

I'll take a look at the Taylor kit again.

I'm wondering if the 300 ppm is simply the normal range of error. I think I remember years ago being told by the pool store that installed our system (I was having them test salt back then; they were using the Taylor kits) that it was normal to see a variation of 200 ppm or 300 ppm.

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Originally Posted by JimK

I'm wondering if the 300 ppm is simply the normal range of error. I think I remember years ago being told by the pool store that installed our system (I was having them test salt back then; they were using the Taylor kits) that it was normal to see a variation of 200 ppm or 300 ppm.

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I found an old post somewhere else made by waste that said the moa was 500 on this test (even with the 1766). I think you're probably just fine

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Originally Posted by kelemvor

I found an old post somewhere else made by waste that said the moa was 500 on this test (even with the 1766). I think you're probably just fine

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Great info. Thanks! :)

Test strip are fine IF they are fresh but they do seem to go bad quickly.

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Test strip are fine ...

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Meaning the salt test strips (and borate test strips). In case someone reads this out of context.

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Originally Posted by BigDave

Meaning the salt test strips (and borate test strips). In case someone reads this out of context.

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Good point. Salt and borate are the only strips I use. ;)

If my readings get too out of wack, I'll order the Taylor salt kit and give it a try.

I looked at the past few readings and noticed if the SWCG controller reading dropped 200 ppm so did the strip test reading. In other words, the 300 ppm difference between the controller and the strips has remained consistant, so I think I'm fine for now.

I've read that as a cell ages you can get lower readings, so I'm wondering if the age of my cell is what's causing the difference (this is our 6th season on this cell). Some have suggested only going by the controller reading since for the function of the SWCG this is what matters. However, I don't want to get into a situation of salt being way to high when it comes time to replace the cell. When the last cell died, the only indication I got was an unexpectedly low salt reading.

For now I don't plan to do anything as long as the controller reading and the stip readings (or Taylor kit if I get it) fall within the cell's normal operating range. Does this sound reasonable?