I'm going to add my 2 cents to this, if it's worth even that.

Most SWG pools have a problem with rising pH. This apparently comes from a combination of carbon dioxide outgassing and possibly chlorine gas outgassing. If one is able to lower the on-time of the SWG, then this increases cell life and reduces the rate of pH rise from both aeration and chlorine gas outgassing. Even if we are wrong with the "why", we do know that lowering the SWG on-time reduces the rate of pH rise as we've seen that occur in countless of SWG pools (lowering the TA usually helps as does using 50 ppm Borates).

So how do we reduce the SWG on-time and still maintain an appropriate FC level? We found that having the CYA be higher, even with a proportionately higher FC for the same sanitation and algae-prevention level, results in a net lower absolute FC drop and lets one lower the SWG on-time. The greatest benefit appeared to be as one got close to 80 ppm CYA.

So what about a non-SWG pool? Shouldn't the advice be to have an 80 ppm CYA target there as well? The answer is more complex because there is a downside to such high CYA in that it becomes more unforgiving if the FC drops and algae starts to grow. The required shock level of FC is far higher. Such high CYA pools CAN be managed and some people do that in order to minimize their absolute FC drop (i.e. to minimize chlorine usage in very sunny areas), but it is riskier in a manually dosed pool where one can more readily miss a dose or otherwise have the FC get too low compared to an SWG pool that is more constantly being dosed (and where there may be some benefit from super-chlorination of a portion of the water through the SWG cell). There is still the same problem with shocking to get rid of algae in an SWG pool with 80 ppm CYA, but the risk (likelihood) of needing to do that is lower than in a manually-dosed pool.

It's a risk/reward tradeoff and the chances of having a low FC in a manually-dosed pool are higher and the benefit of a higher CYA in such pools is lower since they don't typically have as much of a pH rise problem. It is not, however, an absolute "don't use 80 ppm CYA in a manually dosed pool".

So now back to Brad's situation. If he isn't seeing a pH rise, then there is less need for the higher CYA. The only possible benefit would be a longer cell life and that's only IF the higher CYA resulted in a lower chlorine demand in HIS pool such that he could lower the SWG on-time. It is perfectly reasonable to have an SWG pool run at 50 ppm CYA instead of 80 ppm CYA so long as the pros/cons are understood and the specific situation is taken into account. As waterbear noted, even some weekly pool chlorination companies (often using chlorine gas) use 100 ppm CYA in hot desert areas very successfully with an FC that goes from 14 ppm to 4 ppm over a week so no one "rule" is absolute.

I don't see an inconsistency in the advice that is given, though it may upon first appearance look that way. There are multiple issues and risk/benefit concerns in non-SWG vs. SWG pools and this leads to different "general" recommendations -- but one can certainly stray from these so long as one understands their situation clearly.

Richard

Since I somewhat started this thread, maybe I should finish. CYA high... CYA low... For my pool my CYA was at 60ppm. My Goldline Aquarite (a new cell about 3 months old) was not producing enough chlorine to keep up and I had to compensate with liquid chlorine every week. That was running at 10-12 hours @ 100% for April and part of May of this year (San Diego County). The only thing that I am doing different now is that I purchased a different SWG and now I am at 6 hours of pump time and 40%. My FC is at 5-6ppm and my CYA is still at 60ppm. I am sure that CYA levels do make a difference but every pool is going to be different based on it TDS. A pool that has CH at 900ppm and one at 300ppm is going to react different to chlorine, MA and CYA. Theory is one thing... application is another. All I can say is I changed ONE variable and it worked for me.

thnaks richard and slap.

as i said, i was willing to agree to disagree. And..for the record, i understand all of this, it aint rocket science folks. I see a few moderators here are know it all and heavy handed. ok, i can deal. As i said, i was willing to drop it and move on. but, alas, no. ok, nuff said. i'll run my cya at 50 and be just fine. as i said, i think some of you live and breathe this as i see by the number of posts.

FWIW, the brand of generator does matter i think in how much is produced on what setting.

Brad, I've kept my mouth shut thus far, but I'll just say this.

You've been on this forum for all of four days and 20 posts, more than half of which have beenEdited for politeness. JasonLion.

You've made a lot of assumptions based on Edited for politeness. JasonLion, because I'm fairly certain you haven't read the THOUSANDS combined posts of the Moderators. Instead you intend to ridicule us based on the number of our posts?

We are unpaid volunteers, trying to help people figure out what's going on in their pools. Most of them don't have chemistry backgrounds, and most of them have been grateful for the help. Few have laid out the judgemental and negative remarks that you have managed in your short time here.

I can appreciate that you feel you were unjustly attacked, but I can assure you that most of the issues stem from miscommunication and assumptions regarding the intent behind certain posts. You don't know any of us or our personalities or "style" when it comes to offering advice, you haven't participated in this forum long enough to know.

Perhaps if you perused a while before offering blatent challenges, you would know our personalities better and not have become so offended by some of the comments.

This isn't about who's right and who's wrong. There isn't any need to insult the Moderators on this forum. If you don't like it here, you are free to find another forum.

Thank you Jason!

CH is not going to have any real impact on chlorine or CYA, nor will TDS. I am not sure why you included muriatic acid. Perhaps you meant pH? Niether the CH nor the CYA level in the pool will be affected by the addition of muriatic acid, nor will they have any effect on when MA is needed for pH adjustment. However TA (bicarbonates) will.
Actually, TDS is basically a bogus measurement. It is not the Total amount of dissolved solids that matters but, rather, their makeup. Realize that when we speak of TDS we are really speaking of the ionic species in the water. If these are basically chloride, sodium, magnesium, lithium, and possibly borate (to name the most common innocuous species) then they will have minimal impact on water chemistry and, in fact, the vast majority of the ionic species present in most pools are sodium and chloride.
However when we have large amounts of calcium, bicarbonate, cyunurates, nitrates, and sulfates we can have negative impacts on our water chemistry and stability. Each of these has a different effect on our water. However, the most common effect attributed to high TDS is directly attributable to high CYA levels and too low a FC for the CYA, which is commonly what happens when a pool is overstabilzed by over use of trichlor.
Since stabilized chlorine causes the salt level of the pool to rise by adding both sodium and chloride ions the high TDS that is caused by this actually become a proxy measurement for the high CYA that the stabilized chlorine contines to add. and the problems are from the CYA and not the TDS. As the TDS rises so does the CYA! Of course if the calcium or bicarbonates are high there will be other sets of problems but these are NOT the problems that are normally attributed to high TDS (dull water, uncontrollable algae, cloudy water, chlorine not holding, high CC)--all these are directly caused by overstabilziation and not the high TDS, otherwise SWGs would not work at all since every salt pool start out being too high in TDS according to what industry standards for acceptable levels of TDS are!

I suspect that the variable that you changes was the amount of chlorine being generated by the cell. It is possible that the new unit you have does generate more chlorine per hour than the Goldline unit or it is possible that your old unit was not generating up to par anymore because it was being used with suboptimal water chemistry for an extended period of time.
Finally, it is not theory but based on much practical evidence that the higher CYA levels have been shown to be effective and also that the greatest effect was seen at 80 ppm vs even 60 ppm as chem geek noted above!

now this might be a bit controversial, but as far as SWG is concerned, there can be no CYA whatsoever in the pool. it just means your chlorine will disappear faster, so you just need to buy a bigger SWG like salp did

Quit startin' trouble

It is important to note that you are speaking about the proper operations of the SWG cell taken in isolation, and not speaking about the proper operation of the pool as a whole.

Yes, but when you put that cell in real life conditions in a pool and the pH keeps spiking (which it will) which then causes scale deposits to form (which it will) in the cell you have to admit that this will take it toll on the cell and have an effect on output (which it will).

You know as well as I do that the effects of no or low CYA extend to more than just how long the chlorine will last in the pool and affects several aspects of water chemistry!

And just to be clear, the CYA effect has to do with protection from sunlight. If there is no direct sun on the pool (including being indoors), then there is no need for the higher CYA level since the SWG on-time will already be low and not helped by a higher CYA. We at first thought that there might be some direct CYA effect with chlorine in the cell, but that was proven false by Mark's experiments (and by other non-SWG pool users who saw net absolute chlorine usage drop at higher CYA). So for SWG pools not in sun, a CYA of 30-50 ppm with an FC of 2-3 ppm would be fine.

But this would not be an 'outdoor pool' in the strict sense of the word since it would have to have some sort of UV blocking sun cover over it such as a canopy. If there is no cover over the pool it will have some exposure to UV light

FWIW,

i guess i started this kinda. I took some measurements to see what happened over about 24 hours with pool use. Yesterday morning i tested pH and Fc before i went to work and the pump had been on for an hour.

pH 7.6
FC 6

Test results last night.

TA 80
pH 7.6
FC 5
CC 0
CYA 50
CH 130
Salt 3300

That was after being in full sun all day, 2 adults and 2 children in for 3 hours, on and off.
Intellichlor IC 40 was set on 10% from 7 am to 7 pm (my pump run time). Water is crystal clear.

This morning, after 1.5 hours pump run,

FC 5.5
CC 0
pH 7.6

correct. that's why I said "as far as SWG is concerned"

There are ways to mitigate all of those risks Of course putting CYA in is the easiest and cheapest, but if one insists on running without it or low concentration - it's not the end of the world. He just needs to realise what the consequences are, and what needs to be done to balance the water chemistry.

Buying a larger chlorinator will certainly help to prolong the cell life

I gotta say, that statement is VERY TRUE

I dnt have a fancy test kit. I use a good name brand strip and have been for the last 7 years with zero problems... Just test it once a week, make sure the levels are WITHIN range and ENJOY THE DARN thing

Heckpools,

I am glad this subject is already in "agree to disagree" because I would have a difficult time finding a subject on which I disagree more.

1. Don't confuse homeowner maintenance with what you do for a living....the end result may be the same but the approach isn't.

2. This forum is packed with anecdotal stories of pool owners who have been using strips and have gotten in trouble because of it..........not one case, not two cases, but time after time where test strips are simply inadequate for the methods taught here.

3. That's your choice to use test strips....there are hundreds on here who would disagree and choose to more accurately understand the parameters of their pool water.

4. Of course I have an agenda since I sell one of those "fancy" test kits. I hope you will believe I would make precisely the same post if I had never sold a kit in my life. If you would like some verification of that, look back at the old Poolforum and search some of my posts before TFTestkits ever existed. A really good kit was my single best purchase for my pool (from Ben Powell) and it remains so today.

It was thinking exactly this way that I ended up with a problematic pool, which eventually caused me to search the internet seeking a solution... I found the Pool Forum and a post about TFP. Here I am.

I would never recommend strips much less testing once a week, to anyone.