New pool and chemical question

[CanuckPool]

Before I pose my question here are my pool stats

16x34 IG pool with SWG

latest results

FC 4.92
TC 4.97
CC 0.0
pH 7.80
hardness 170ppm
Alk 210 ppm
CYA 15 ppm
Salt 2900 ppm

They suggested I use a product called AQUA pH minus to bring down the Alkalinity to between 100 and 120 ppm which is fine. I just wondered if there was a cheaper product that I could use to control the pH and Alk. I am a newbie but still trying to save on costs. I just bought 8kg which is about 17lbs of this stuff for $30 canadian, is that a good price, is there something cheaper? Can i use muratic acid is it cheaper per treatment?

Since I have a SWG I know the tendency is for it to drive the pH up, so I am sure we have to stock up on the appropriate chemicals.

Thanks

[waterbear]

Muriatic acid is much cheaper and much more effective. It is also the first choice with a SWG since it will not add sufates to your water. pH minus is sodium bisulfate.
When you use muriatic acid to neutralize the high pH the end product is once again salt!
BTW, most SWG manufacturers remcommend running your CYA at 60-80 ppm. This will allow your cell to operate at a lower setting and will help keep the pH from rising as quickly.l
To lower your TA see this thread
http://www.poolforum.com/pf2/showthread.php?t=191

[KurtV]

Canuck,
Neither pH Minus nor muriatic acid will lower you alkalinity permanently. Those products are used to lower you pH. To lower alkalinity you'll have the follow the procedures outline here: http://www.poolforum.com/pf2/showthread.php?t=191.

If you're not have trouble controlling your pH (unlikely, it will probably tend to rise with your high alk and the SWG) and you're not getting calcium build up (scale) on anything, you might be able to live with your alkalinity as it is.

Best of luck.

[CanuckPool]

I read that post, it seems the only difference is that you aeriate while you are lowering your pH/Alk and to do it gradually.

Can lowering your Alk this way keep it permanently low? or is it an ongoing type treatment.

[waterbear]

depends on what is making your ALK rise. If your fill water is high ALK then you will have to do it every time you add water.
Also, the difference between the method in the thread and just adding the acid is that the method in the thread actually works!

[KurtV]

Yes, that will lower your alkalinity permanently (or at least until something else, such as your fill water, changes it).

Are you having trouble keeping your pH down or with scaling?

[CanuckPool]

The pool is only 2 weeks old, so I am trying to get a handle on getting it in order. The pH seems to always creep higher and higher as the days go on, I suspect its the SWG driving it up as the pool guy said. It appeared my CYA was too low initally (1 week ago it was at 5ppm) so we are currently trying to bring it up with Stab. Its at 15ppm now. If my pH always wants to move up, will that mean my Alk will always want to move up? or once you get your alk down, will it stay down unless fill water has high Alk. I am finding it confusing as alk and pH are connected... somehow.

[KurtV]

I'm a little over my head here and Evan (Waterbear) will probably answer this more thoroughly and accurately, but here goes.

The alkalinity and pH are related and will move together somewhat but they're not the same thing. For our purposes here, alkalinity is a measure of the resistance of the water to pH change; higher alkalinity will make the pH more difficult to change and vice versa. It will move down a little when you add acid to lower the pH but not radically and it will rise a little as pH rises. When you use Ben's technique for lowering alkalinity, the alkalinity will drop along with the pH but it won't rise again with the pH (or at least not as much) because you're aerating the water and releasing some of the carbonate that was in the water into the air.

I think (that usually gets me into trouble) that with your high alkalinity your water will probably tend to an always rising pH. But, if you don't have to add large amounts of acid often to control the pH and you don't have scaling, you might want be able to live with your alk as it is. If you find that dealing with the high alk is a big hassle, use Ben's technique to lower it.

There are a bunch of fascinating threads concerning alkalinity and pH on the forum here if you really want to understand this stuff. Look especially for posts by chemgeek and waterbear.

[CanuckPool]

Thanks Kurt, what you said actually makes sense, even to a layman like me. Sometimes the experts explain it with too much tech jargon and I tend to get lost. I am going to try Ben's technique when I get home and I will let you now how it goes. So far we have been pretty happy with our pool, just getting to know how to maintain it is the key.

[KurtV]

Just keep reading here and you'll have a firm grasp on it in no time. If you haven't already read them, the sticky threads at the top of the chlorine and testing forums are a great primer.