Newbie just beginning to understand "free" and "total" chlorine. . .

[aylad]

Combined chlorine is chlorine that is actively engaged in oxidizing goo from your water. The best remedy for it is ...more chlorine! It just means that the chlorine is doing its job. Usually if you have CC more than .5 ppm, we suggest shocking the pool until that CC level drops to zero. If it's less than .5, as in your case, just keep your chlorine levels where they need to be, keep the pool uncovered, and they'll take care of themselves. (By the way, there's no such thing as "chlorine lock", and the non-chlorine product they sold you was a really expensive way to do what you could have done with plain, generic bleach).

The FC and TC tests that we recommend are the DPD-FAS test kit (K-2006).(See the test kit link in my sig). It uses a scoop of powder to turn your sample pink, then you add drops of the reagent until it goes clear. No comparing yellows.... the complete kit is the K-2006, but if you have a drop-based kit already, the K-1515 is the standalone chlorine part of the kit. You can get them at a good price online using the Amazon link in my sig.

One of the main caues of slightly greenish but not cloudy water is the presence of metals. What is your source of fill water, and is there any known copper or iron in the water? Have you used anything containing copper (algaecides, trichlor tabs, any other type of "dual action" product) that contains copper?
!

[Hainsworth]

Thanks for the speedy reply! Interesting that you mention metal. I left it out of my original post, but the last water test said 0ppm copper and .31 ppm iron. The pool store considers the limit for irom to be .30, so they gave me a "metal out" product which I used. Our fill water source is our well, which is generally good (has been professionally tested for every contaminant known to man, as well as minerals and metals), but occasionally contains a little iron (seasonally depaning on groundwater levels and was <.03 ppm for Iron in January of 2012). Also, water gets to pool through hose on frost free hydrant which has some parts that could leach. My husband just added water (for the first time this year) today with that hose! Could the addition of new water w/ metals be reacting to earlier administration of "metal out" product? Maybe I should just let the pump go and see what we've got in 24hrs?

I will plan on getting the chlorine test you recommend and shock with bleach. Does it matter what bleach you use - obivously not the funny ones with added lavender scent, etc - but is there really any difference between the "splash-less" and all the other permutations out there these days and regular old bleach? I don't want to add anything that might cause any problem with the SWCG cell.

Thanks again.

[waterbear]

I will plan on getting the chlorine test you recommend and shock with bleach. Does it matter what bleach you use - obivously not the funny ones with added lavender scent, etc - but is there really any difference between the "splash-less" and all the other permutations out there these days and regular old bleach? I don't want to add anything that might cause any problem with the SWCG cell.

Yes, there is!!! You want plain unscented, un-splashless chlorine bleach! All the others have additives that can cause foaming or worse and are not considered to be sanitizers.

What make of SWCG do you have. CYA of 40 ppm seems on the low end and it is a good rule of thumb to run the CYA at the manufacturers high end which is usually 75 to 100 ppm depending on the make.

[Hainsworth]

Thanks Waterbear!

That's what I thought about the bleach, but I want to make sure I ask all the questions (even dumb ones ) so that I get this right! My SWCG is a Pentair Intellichlor Model IC 40. I checked the manual and it does say that optimum CYA levels for the unit are 50-80 ppm. Why should I aim for the manufacturer's high end? I appreciate the education.

[aylad]

Having the CYA at the high end of the manufacturer's recommendation will help the cell last longer.

Oh--and there are not dumb questions, when it comes to pool care!

[waterbear]

No only will it help the cell live longer, it will indirectly give you better pH stability. It's a lengthy explanation that I won't go into now but once things slow down in the fall I will be glad to explain it!

Also, as a rule of thumb you want to keep your FC at 10% of your CYA level (as a minimum) or a bit higher for a margin of safety.
Order the K-2006 and do your own testing. Pool store testing is often suspect (I know this first hand, having worked in pool stores!)

Iron in your water can cause the water to turn yellow and can casue yellow to orange stains...combine that with a blue liner and you have your greenish color. Using a metal remover on a regular basis is the right thing to do but you want to use one that is HEDP. Many of the 'metal remover' products are blends or ineffective chamicals such as EDTA that break down quidkly in the presense of chlorine so they do not do much good at all. Exactly what brand of metal remover did they sell you?
If you prefer you can get this one from Amazon, it IS HEDP:

KemTek 20% HEDP @ Amazon

You want to use the initial dose of 1 oz per 1000 gallons (for your pool 2 quarts) and then a maintenance dose of 1/4 that amount ever week or two of HEDP.

[Hainsworth]

Thanks a lot to aylad and Waterbear! Waterbear, you may be on to something with the iron/yellow water over blue liner idea, but so far the green is very faint and only really noticible on the (white) stairs and swim out. If the water hadn't been perfectly clear before I probably wouldn't even say that the water was green. The Metal product they sold me was SunGuard Metal-Out Plus, which I just found lists NO ingredients on the bottle (or the SunGuard website). . . hmmm. They had me use one quart for my 21,000 pool.

I think the "green" is less noticible today. pH is back up to 7.9 (tested w/ newly calibrated digital meter I had to get for household testing because we needed acid neutralizer for house - well is 4.9!!) which is what it was before last pH correction. After reading up on pH here on the forum, I've decided not to worry about that right now. Even with the (untreated) well water as fill last year, we were always on the high end 7.6-7.8 and had our lowest reading ever on opening this year - 7.5, so maybe that's just what my pool "wants" to be. I'm on my way to shock (bleach) and when my new super duper test kit gets here (K-2006) I'll check CYA, ALK, and FC/CC and adjust accordingly. Then I'll see where we are on pH. Thanks everyone!!