Help. Cya 125 !

[~StillinSaigon~]

My 86 Year Old Father has run the gamut of attempting to resolve an Algae and "Bluish-Green" Cloudy 30K In-Ground white Plaster swimming pool with a Hayward #310 Pump with an Auto-Chlorinator. The 500 lbs. of sand was just changed (due to the problem), two weeks ago. The pool is 9 years old. The water readings as of last night were as of follows:

FC 4.1

TC 4.3

CC 0.2

Ph 7.3

Hardness 260

Alkalinity 53

CYA 125

He is using 3 inch (in-line) Trichlorchiro-S-Triazinetrione Pucks, as well as Granular, Sodium Di-Chloro-S-Triazinetrione Hydrated. In accordance with the Pool Facilities here in Richmond, Virginia, he has added 3 - 4 pounds of the Granular mix to the Pool Surface itself. As of this writing, he is taking another Water Sample in to be tested. The pool water right now is Bluish-Green and Cloudy and cannot see the bottom at all. In the Forum Posts I've read thus far, it seems that a partial draining is in order. I've also read about Ammonia not being able to be read by the top of the line testers. I'm an FNG (Effin' New Guy. Sorry, I'm a Former Marine and old terminology dies hard), yet when the Gurus here speak of the relationship of CYA and Ammonia, how does this affect the pool's water? I understand the CYA rate is off the scale, yet insofar as bacteria caused by human waste (urine), no one under the age of 22 has ever been in the pool. If there's a direct relationship between CYA and Ammonia, should an Ammonia Tester be purchased from an Aquarium store to help you guys with this dilemma?

I'm totally new to "Pool Chemistry" and am desperately asking for some help to have this Pool up and running at some point this Year. Please lay it out to me in "Layman's Terms" for my Father and I are not Experts, such as you.

Much Thanks in Advance,

~StillinSaigon®~

[chem geek]

You won't have any ammonia in the pool when you have measurable Free Chlorine (FC) so don't worry about that. Others will be along shortly to help you out -- you'll want to wean yourself off of Trichlor and Dichlor since they increase the CYA level and you'll need to dilute your pool water to lower the CYA level, but in the meantime can keep the FC level up to compensate. You can read the Pool School to learn more until others chime in to help.

[PaulR]

You have several issues, but first things first. The key relationship is CYA to FC. CYA holds some chlorine in "reserve" protecting it from sunlight, and the remaining chlorine is what's on the "front line" so to speak. The proportions are basically linked to the CYA level. The trouble in your father's pool is that you have too much in reserve and not enough on the front lines killing off the algae. As the front-lines chlorine gets used up, more is released from the reserves, but it doesn't happen fast enough to stay ahead of the algae. In order to reduce the proportion of chlorine held in reserve, you need to reduce the CYA level. The only practical way to do that is to drain water out of the pool and replace it with fresh. (Tap or well water has no CYA.) How much to drain depends on how high your CYA is.

It's possible that your CYA is really 125, but the typical CYA tests are not reliable above 100ppm. I suggest you get a sample of pool water, dilute 50-50 with tap water, and test that mix for CYA; double the result. That will give you a truer indication of your CYA level.

Never ever use "dichlor" again. It adds more CYA almost as fast as it adds chlorine, and you have too much CYA already. For shocking the pool, you can use 'liquid chlorine' or regular unscented household bleach (both are Sodium Hypochlorite, just in different concentrations). The advantage of liquid chlorine is that it adds ONLY chlorine; nothing else worth mentioning. The disadvantage is having to lug all those jugs around, and if you splash any on your clothes they will be permanently spotted. A second-best option would be Calcium Hypochlorite, a powdered chlorine; this does not contribute to your CYA, although it does contribute to your Hardness. You have some leeway in your hardness, so I think using Cal-Hypo for shocking would be fine.

I'm sure you use "trichlor" because it is very easy; I have fallen into that particular trap myself. Each 3-in 8-oz puck in your pool is worth about 2ppm chlorine and 1ppm CYA. SO if you go through, say, 5 per week, you can see that every 2 weeks you are adding about 10ppm CYA. It does not take long to build up an excessive CYA load again. That said, if you are willing to periodically drain some water out of the pool and replace it, to lower the CYA levels as they build up, you could probably continue using the trichlor.

After you lower your CYA level, then it will become feasible to kill off the algae with very high levels of chlorine, using either liquid chlorine/bleach or cal-hypo. It really won't be practical until you have lowered the CYA, however.

I see chem geek has already mentioned Pool School which is where I learned most of what I know. It's a lot to take in all at once, and we'll try to work you through it step by step.

--paulr