Are borates and salt algicides?

[sks23cu]

This past Spring I brought my pool's borate level up to 30 ppm and salt up to 1000 ppm.

I've noticed that the pool remains crystal clear even if the chlorine levels drop way below recommended.

Yesterday I tested and the chlorine was 0 ppm on the Chlorine Drop test. But the pool was crystal clear.

With a CYA level of 40 ppm the Chlorine / CYA Chart recommended chlorine level is about 5 ppm. So I dutifully added bleach.

In addition to algae, I suppose we have to worry about other microbes. So maybe we need the chlorine levels to kill them. (?)

But it is attractive from a cost standpoint to think that we may need to use next to nothing for chlorine. Along those lines, I'm down to running the pump and filter to 3 hours per day, and I think I could go lower. The back pressure remains low so I've not had to recharge with new diatomaceous earth, either.

Of course another factor is that we have a very light swimmer load (my wife and me, except a week with neice and nephew and parents). But that didn't keep the pool from getting cloudy occasionally last year with the same swimmer load!

So maybe the Chlorine / CYA Chart needs two more dimensions: borate and salt. (?)

 

[frustratedpoolmom]

The salt doesn't affect algae or not. You are taking several risks by allowing the FC to drop that low.

You can have nascent algae, especially when the FC is allowed to drop to zero frequently. There is no benefit of running your pool this way, you are taking too many risks.

You should have at least one turnover of water per day at a minimum, regardless of how long of a pump run time that is, have you calculated your pump run time to determine if that short of a time is enough for a complete turnover?....I think the borate level has to be 50 ppm to see a pronounced affect.

Perhaps you have just been lucky. I think you are tempting fate.

 

[duraleigh]

This forum is filled daily from May until September with posters who have a green and/or cloudy pool because they have failed to keep adequate chlorine levels.

For you newbiers who read this, please do not think you can keep your pool sanitary and algae free with some "magic bullet" or combination of "magic bullets.......you cannot.

It is often quite difficult to help newbies understand the need for adequate chlorine and how essential it is to the type of pool management we champion. We advocate this for one very, very overwhelming reason......it works! Not only does it work, but it works time and time again year after year.

To suggest an alteration to that teaching only further adds to the confusion. I have seen at least two posts this summer wherein a newbie, after doing just the wrong amount of homework, has decided to put borates in his green pool (totally neglecting his lack of chlorine) because it "sounds good" to him/her......i.e. the magic bullet has been found!!

I do not think it is helpful to suggest borates and/or salt reduces the need for chlorine. To my knowledge, salt is completely irrelevant and, while borates appears to provide some enhancement to chlorine's effectiveness (I'm not 1000% convinced but I'm open to learning), the fact remains that you still need chlorine and you still should apply chlorine at the levels suggested in the CYA/Chlorine chart in Pool School.

The pool management techniques taught here work. They work over and over again year after year. (Yeah, I know, I'm repeating myself....it's for emphasis) Failure to use them smartly usually involves an unsanitary pool and green/cloudy water......sooner or later.

 

[frustratedpoolmom]

Steve, please check your PMs, upper left corner.

 

[sks23cu]

To my knowledge, salt is completely irrelevant

Then why does the Chlorine / CYA Chart say, "Most saltwater chlorine generator (SWG) pools appear to prevent algae at a lower minimum FC level compared with the minimum FC column for manually dosed pools."?

When salt is dissolved in water it becomes Sodium and Chlorine ions. What does the SWG do to it that changes that? If it creates Chlorine molecules, what does it do with the Sodium? Isn't Sodium in molecular form toxic?

So if SWG doesn't create Chlorine molecules from the ions, why wouldn't adding salt to a non-SWG pool have similar effects of lowering the chlorine level needed?

BTW, I've been following the BBB method every since I found it on Ben Powell's site years ago.

So I'm no newbie.

 

[Ohm_Boy]

Well, for one thing, the FC levels with an SWG are more constant, as opposed to the constant reduction of levels in a non-swg pool so with a more constant overall level, algae and other nasties have less of an opportunity to start. Secondly, the water directly in the cell becomes superchlorinated as it is treated. It is localized to the cell but it's still 'shocked', if you will, and helps oxidize whatever is in the water.

 

[JasonLion]

Pure sodium is dangerous, but it isn't actually toxic in the usual sense. The intensity of the reaction it has with water can be dangerous, but it isn't a poison. Sodium ions in water are harmless and non-reactive. The sodium simply sits in the water as ions and does nothing.

The SWG converts chloride into hypochlorous acid, the active disinfecting form of chlorine. When the hypochlorous acid is used up by either sunlight or helping to disinfect your pool, it turns back into chloride.

No one really knows why SWG pools can run at lower FC levels, but it does work. I have heard several different theories, some of which are commonly repeated as "the answer", but no proof of any of these theories exists. The required FC levels were determined experimentally. The chemistry remains unexplained.

Adding salt to a non-SWG pool does affect the subjective feel of the water, but has no effect of algae or the required FC levels.