What's The Deal With Stabilizer?

[Brooklinite]

Hi all,

I've had a salt-water inground pool 14x28 (not sure how many gallons) for a little over a year and I'm confused about stabilizer. The pool has always worked perfectly, crystal clear, maintains a normal level of chlorine, water test's fine at the pool store, no issues whatsoever but I've never put stabilizer in it. We had a conventional chlorine pool when I was a kid and I used to look after it and I don't ever recall putting anything but liquid and crystal chlorine and PH up and down.

Do I need this stuff? If so, why???

THANKS!

[chem geek]

Perhaps stabilizer was added to your pool when it was first filled with water (i.e. on startup). The Cyanuric Acid (CYA) aka stabilizer aka conditioner will not go away except by dilution so some may still be there. Without stabilizer, the chlorine will break down quickly by the UV rays in sunlight -- losing half the chorine every half hour in direct noontime sun. Also, without stabilizer, the pool is essentially over-chlorinated and much harsher on skin and hair and swimsuits. You should consider getting yourself a good test kit that includes a test for CYA such as the Taylor K-2006 you can get here or the TF100 kit you can get here.

[TxRS]

Pools can run just fine on very low stabilizer levels. You get maximum stabilization levels at 30ppm so there really is no reason to run higher and plenty of reasons not to.

If you maintain good chemistry and everything that entails without adding stabilizer, then don't fix what isn't broke.

[waterbear]

Pools can run just fine on very low stabilizer levels. You get maximum stabilization levels at 30ppm so there really is no reason to run higher and plenty of reasons not to.

If you maintain good chemistry and everything that entails without adding stabilizer, then don't fix what isn't broke.

Not quite true for a pool with a SWG, they tend to do better for several complicated reasons with hgher CYA levels of around 50-100, depending on the particular model. The majority of them work best at 60-80 ppm. The advantages to higher CYA levels with salt pools include longer cell life, better ph stability, and possibly shorter pump run times to name a few. The reasons get quite techincal but many have to do with the rate of CO2 outgassing from the water. The higher CYA levels indirectly minimize it considerably.

[chem geek]

Pools can run just fine on very low stabilizer levels. You get maximum stabilization levels at 30ppm so there really is no reason to run higher and plenty of reasons not to.

If you maintain good chemistry and everything that entails without adding stabilizer, then don't fix what isn't broke.

[EDIT] Apparently, I wrote this as waterbear was writing his post above. [END-EDIT]

This is normally true for manually dosed pools, but we found out that there is a significant increase in protection of chlorine from the UV of sunlight somewhere in the range of 50-80 ppm. This is above and beyond the theoretical protection predicted from the equilibrium chemistry and my best guess is that it is a shielding effect of the CYA protecting the lower depths (though this requires a lack of mixing near the surface). We discussed this issue in this long thread and then some experiments were done to see if the cause had anything to do with the SWG itself (it didn't) in this post.

In commercial pools, a maximum stabilization at around 20-30 ppm is seen because the higher bather load has a larger chlorine loss than that from sunlight in that CYA range so any increase in CYA doesn't seem to do much good. This is not the case in residential pools. The main reason to have a higher CYA level in an SWG pool is to allow for lowering of the SWG output since that reduces the production of hydrogen gas bubbles in the SWG which reduces aeration which pulls carbon dioxide out of the water and causes the pH to rise.

I was surprised by this finding and had to eat crow about a theory I came up with to explain it that turned out to be dead wrong as Mark's experiment proved.

Richard

[justawildchild]

Pools can run just fine on very low stabilizer levels. You get maximum stabilization levels at 30ppm so there really is no reason to run higher and plenty of reasons not to.

If you maintain good chemistry and everything that entails without adding stabilizer, then don't fix what isn't broke.

[EDIT] Apparently, I wrote this as waterbear was writing his post above. [END-EDIT]

This is normally true for manually dosed pools, but we found out that there is a significant increase in protection of chlorine from the UV of sunlight somewhere in the range of 50-80 ppm. This is above and beyond the theoretical protection predicted from the equilibrium chemistry and my best guess is that it is a shielding effect of the CYA protecting the lower depths (though this requires a lack of mixing near the surface). We discussed this issue in this long thread and then some experiments were done to see if the cause had anything to do with the SWG itself (it didn't) in this post.

In commercial pools, a maximum stabilization at around 20-30 ppm is seen because the higher bather load has a larger chlorine loss than that from sunlight in that CYA range so any increase in CYA doesn't seem to do much good. This is not the case in residential pools. The main reason to have a higher CYA level in an SWG pool is to allow for lowering of the SWG output since that reduces the production of hydrogen gas bubbles in the SWG which reduces aeration which pulls carbon dioxide out of the water and causes the pH to rise.

I was surprised by this finding and had to eat crow about a theory I came up with to explain it that turned out to be dead wrong as Mark's experiment proved.

Richard

Does this mean that my SWG is causing the air bubbles coming out of my return jets, and this is because my stabilizer levels are too low?

[chem geek]

Yes, your SWG produces hydrogen gas bubbles whenever it is on and this aerates the water which ultimately causes the pH to rise. These bubbles have nothing to do with the CYA level. What a higher CYA level does is reduce the amount of breakdown of chlorine from sunlight and that reduction lets you lower the SWG output (i.e. it's on-time) and THAT means less total hydrogen gas bubbles. Higher CYA --> Less chlorine loss from sunlight --> Shorter SWG on-time --> Less hydrogen gas bubbles --> Less aeration --> Lower rate of pH rise.

[EDIT] Some recent analysis shows that it isn't the hydrogen gas bubbles as much as undissolved chlorine gas bubbles that cause the pH rise, but the first part of the sequence above still holds: Higher CYA --> Less chlorine loss from sunlight --> Shorter SWG on-time --> Less chlorine gas bubbles --> Less loss of chlorine gas the air --> Lower rate of pH rise. [END-EDIT]

[Toddro61]

I have a salt water chlorinator and I used to have a lot of stabilizer (50-80ppm) in the pool which is what the instructions with the chlorinator recommended. When it was at this level, I always got algae despite the fact the chlorinator was putting out a lot of chlorine. The stabilizer binds up the chlorine and makes it inactive.

I let the level of stabilizer drop to zero, and now I never have any problems with chlorine or algae.

If you don't have a problem, I would not add stabilizer. I live in Central Texas too where the sun is a beast.

[waterbear]

I have a salt water chlorinator and I used to have a lot of stabilizer (50-80ppm) in the pool which is what the instructions with the chlorinator recommended. When it was at this level, I always got algae despite the fact the chlorinator was putting out a lot of chlorine. The stabilizer binds up the chlorine and makes it inactive.

I let the level of stabilizer drop to zero, and now I never have any problems with chlorine or algae.

If you don't have a problem, I would not add stabilizer. I live in Central Texas too where the sun is a beast.

Where were you running your FC? I bet it was low. You want to target 3-5 ppm FC with a SWG. The worst side effect of running the stabilzier too low with a SWG is hard to control pH rise, early cell failure, and scaling problems from pH rise.