Salt System newbie

[chem geek]

If you find that the pH tends to rise over time and if your pool is exposed to direct sunlight, then having the CYA in the 60-80 range, especially 70-80 ppm, has the chlorine protected more from breakdown in sunlight. Even proportionately raising the FC level to 4 ppm minimum with 80 ppm (for an SWG pool), there is less absolute chlorine loss.

The lower chlorine loss lets you turn down the SWG on-time and that reduces the rate of pH rise (from whatever the cause -- could be more outgassing of either carbon dioxide through aeration or of undissolved chlorine gas).

Adding 50 ppm Borates can also help reduce the rate of pH rise through two effects -- it acts as a pH buffer and it is a mild algaecide so may further reduce daily chlorine usage. It's also insurance since at the higher CYA level you want to make sure you don't have the FC drop below the minimum since fighting an algae bloom takes a lot more chlorine (higher FC level) when the CYA level is higher.

As for eyes burning at 100 ppm CYA, that probably wasn't a direct result of the CYA but the FC probably wasn't high enough (i.e. was below 5 ppm) and that meant that the active chlorine level could have been so low as to have more chloramines in the pool and those can be irritating to the eyes. Either that or the pH may have been off (too high or low). If you find any problem at 80 ppm CYA with 4 ppm FC, try increasing the FC target to 6 ppm, but I doubt you'll need to do that since there are many, many people with SWG pools that mostly operate with 4 ppm FC and 80 ppm CYA without any issues.

[BigTallGuy]

I have only had my SWCG for two weeks and the "official" swimming season hasn't started yet. I am watching my chemicals very closely including the pH levels. My 24' round AG pool takes direct sunlight for the majority of the day and I still consider myself to be in the Start-up mode.

Here are my Thoughts. I am not trying to be arguementative, but I am always open for a nice discussion and maybe I'll learn something along the way.

My overall philosophy is to keep all chemicals to a minimum. I have added seven 40lb bags of salt and I probably need to add another half to a full bag. I am at 3300 PPM of salt and should be at 3500 PPM according to the manual but the low salt light is out. I am reluctant to add more salt as the water already has a slight salty taste to it even though the internet says most humans cannot taste salt below 3500 PPM.

I am at approximately 40 CYA and really don't understand why a Salt system requires more that a traditional Chlorine pool. For now, my SWCG runs 8 hours a day regardless, and if my current CYA levels keep a minimum amount of chlorine in the pool until the pump kicks on and adds more chlorine, then I want to believe I'm good. But hey, they don't call me the BTDG for nothing.

As far as my previous bad experience, I can only tell you that I had my water checked repeatedly and by multiple pool stores and the response was that my water was "Picture Perfect" except for the CYA value and I still had burning eye complaints. I did drain 25 inches of water from the pool, leaving 15-16 inches of water remaining to eliminate the high CYA and still ended up with a reading of 100-110 AFTER refilling.

[chem geek]

As I wrote, the reason for the higher CYA for an SWG pool is to reduce the rate of pH rise by reducing the rate of chlorine consumption thereby letting you lower your SWG on-time.

If you are not experiencing a pH rise that you find intolerable, adding a lot of acid every week, then you can certainly leave your CYA at 50 ppm and keep your FC at least at 2.5 ppm if not 3 ppm minimum. That's perfectly fine and is totally up to you. I was only explaining why a higher CYA is usually done in most SWG pools -- it is a legitimate reason that works well in most cases.

Yours, however, is the only case of stinging eyes from tens of thousands of pool owners that is not attributable to either chloramines (usually from low FC relative to CYA) or an out-of-whack pH. There are many pools with very high CYA levels -- even over 200 ppm in pools using only stabilized chlorine -- and stinging eyes aren't a direct result, though indirectly if the FC is low and Combined Chlorine (CC) is present then stinging eyes are reported. Your experience is very real and there is no question about that -- it may be the CYA or it might not be. Chemical sensitivity is a unique experience and perhaps you have a sensitivity to this chemical.

Also keep in mind that pool store tests are very often wrong. I would only trust your own testing. Though the pool stores usually don't get the pH that wrong (though sometimes they do), they very often get the CYA test very, very wrong. It could have been far higher than 100 and you could have very likely had high chloramine levels as a result. This should not happen if you maintain a higher FC with the higher CYA -- i.e. 4 ppm FC with 80 ppm CYA, but again you do not have to do this -- it's completely up to you.

[waste]

Listen to chem_geek!, you may not always understand the whys - but he won't steer you wrong!

If you follow the advice here, you may add a little more of this or that, but in the end, you'll be using LESS of any chemical than you would otherwise. (quite the conundrum, eh? )

[BigTallGuy]

Thanks Chem Geek for taking the time to help me. I will watch my pH levels and FC very closely. If I find the pH rising, I will certainly add more CYA. I am going to look into buying a better test kit this weekend. I guess the thing that I am starting to understand is that this is a completely new system. I NEVER had to add any acid to lower the pH before with the old chlorine system, seriously the dry acid would literaly harden in the bottle.

I think you guys may have cracked the code, meaning I think I am starting to understand. Waste, Carl, Watermom, thanks to all of you for your help. This is an awsome websight.

[BigTallGuy]

In the infamous words of Gomer Pyle....Well Gooooolllleeeeeeee. I tested My pH and found that it had gone from 7.6 or 7.7 back up to 7.8 or 7.9 in about 1 weeks time. I added Acid and brought it back down to 7.4. So it looks like I'm going to need more Stabilzer. I had my stabilizer level tested again, it kind of blew me away at what the guy did. He filled the test cylinder with my water and added the solution, then he slowly pumped the spoon a couple of times, no more than three, and proudly announced that I had no stabilizer in my pool and then tried to sell me a bottle of CYA. I won't even mention what the results were, as I totally discount this an an accurate test.

So to re-cap, As Chlorine is depleted by UV rays or time or whatever, it does some kind of funky chemical wizardry and burns off the acid or maybe it leaves some sort of alkaline behind. In any case, the pH goes up. The Cyanuric Acid slows down this depletion of Chlorine, and there by slows or stops the pH rise. So, is this process unique to Salt system pools? As I stated before, I never really had to add acid before with traditional chlorine. So did the BTDG get this registered correctly in the old gray matter?

Don't worry Chem Geek, your job is safe, but thanks for your wisdom.

[CarlD]

BTDG:

Relax: there are situations where higher CYA levels are called for. aylad runs her pool high because there's SO much loss due to sun and biologics she needs more stabilization. So she compensates by running a higher residual FC level.

But SWGs need higher CYA levels and lower FC levels. I'm not sure of all the chemistry, but years of watching the SWG people has me convinced.

[chem geek]

The key is being able to turn down your SWG on-time. The higher CYA level should let you do that by greater protection of chlorine from breakdown by sunlight. It's not the higher CYA itself that slows down the rate of pH rise -- it's the turning down of the SWG on-time (i.e. the % on-time) -- the higher CYA is just one way to be able to do that.

[jeffvrba]

It seems to me if I can remember back that far that the Pool store Owner claimed the the higher the TDS reading, the less effective the other chemicals will work, and thus requiring more and more chemicals to keep the pool in check. In all fairness, it was the Pool store owner that suggested that I drain the pool rather than spend hundreds on chemicals. Don't get me wrong, I am not defending these people. When I asked them what I could do about the high CYA level, they wanted to rent me their pump for $30 per day to re-drain the pool again. They would not even let me have the pump for free even after admitting they were at fault.

After my most recent liner replacement and re-fill 2 weeks ago, I took water samples into this same store. You should have seen the look on their faces when I asked for a Salt check. I basically got the Bum's rush because they realized that their gravy train was coming to an end. So to your credit Carl, they get no mo money from me.

I have built an Excel Spread sheet to help calculate the amount of salt needed based upon the gallons of water in the pool that I will share if someone wants to see it. It is actually too large to post. So I would need to e-mail the file.

One more thing, how do I get off of the "Restricted Status"?

I’d like to see that spread sheet but I couldn’t PM you, can you send it to me?

[BigTallGuy]

Yes Chem Geek I agree, you are absolutely correct. I was instructed by the installer to simply run the SWCG for 12 hours a day and forget about it. This took me out at the knees. How does not buying Chlorine tablets save you money if you are spending more than the price of chlorine on your electric bills every month, or if you're pouring gallons of acid into your pool every week? So learning from knowledgeable people is worth its weight in gold.

CarlD, I do realize that different locations, different pool types, and different situations will all affect pool chemistry. My pool is 20 miles east of Phoenix and I am sure that I have my own unique situation to learn and understand. I am relaxed, I am listening, and I am learning, I am still on start-up, I am still a salt system newbie, and don't forget, I am still a BTDG too. LOL. Thanks for your help. We're cool.