I am in charge of two different pools. One has 488600 (swimming pool) gallons of water and is heated, and the other one has 990750 (diving pool) gallons of water and is not heated. They are both old concrete pools. First I must clear out that the swimming pool has a new recirculation system working properly, while the swimming pool has an old recirculation system and the filters' sand need to be changed (Owner hasn't changed it in a long time, but will change the filters later on this year).
These pools usually receive about 600 people per day and exposed to heavy sunlight. "Fresh water" is taken from a pond (Analysis to this ponds will be made next month), but from what I tested with the Taylor kit, it has no chlorine and pH is below 7 (It was too yellow to give a reading).
With the swimming pool:
Pool guys used to alternate between trichlor and calcium hypochlorite (Both granulated). They didn't have a testing kit so I got one and got the following readings:
Cyanuric acid: 85ppm
Calcium Hardness: 190ppm
In a week the pool turned completely green, so we closed the pool and when I tested pH, FAC, CAC it read as following:
I shocked the pool, first I had water replaced to lower the CYA and added 170lb of calcium hypochlorite. FAC went up to 16ppm instead of the 30ppm I was reaching for. I added another 170lb and it went up to 22ppm. Since the pool was not changing and people HAD to use the pool (No option there, I didn't have much time to reopen it) I decided to use 15lb of copper sulphate (I know it is not what TFP recommends, but I didn't have much time). Next day I vaccumed the pool and it was turbid, but not green anymore. I tested again and the readings were:
It is important to point out that the pool was being brushed twice a day.
So, according to the levels I found, everything was in order, except that chlorine was too high (Which made sense due to the amount of calcium hypochlorite used). I decided to mostly use calcium hypochlorite because I didn't want to get levels of cyanuric acid high again, but the pool started to get white and milkysh. Pool guy (He has a lot of practical experience) says it is because of the calcium in it, but I am not quite sure... They swear over trichlor, they even use it to shock the pools, with no regard over cyanuric acid buildup.
Now, with the diving pool:
They alternate trichlor and calcium hypochlorite every other day.
Their readings were:
CYA: Over 100pppm
Pool turned milkish and then turned green (Which is how it is today). Since we ran out of calcium hypochlorite (And can't buy any soon), I agreed to their suggestion of shocking with Trichlor (I know it's not right, but there is nothing else), so they added 75lb last night. With that FAC went to 4.5ppm (Which is nothing to what it should have changed). I thought they didn't add it, so I told them to add 110lb of it (Which they did, right in front of me) to the pool. I tested after a bit more than an hour (Taking into account trichlor takes a while to dissolve, but it only went up to 5.5ppm!! I know trichlor is supposed to go in skimmers, but either pool has skimmers, and they are both stained, so at this moment I'm not worried about the effects of trichlor in the pool's surface... I figured I'd kill whatever is in there with chlorine from trichlor, but at 5.5ppm it's not even close!
My main questions are:
-Is there a reason why 185lb of trichlor will only change FAC by 2ppm? I'm using Chinese products... The supervisor that was before me said that it is because chlorine goes directly into attacking algae and bacteria, but that doesn't make sense to me. From what I understand, high concentrations of chlorine will kill algae and bacteria, but chlorine does not act directly on algae without affecting concentration... Right?
-Why is calcium hypochlorite turning water white and then green if levels of chlorine are on the right level according to the CYA content, and alkalinity, pH and CH are fine as well (As they are in the swimming pool)?
-Pool guys swear that the white stuff in the pool is calcium, but calcium hardness is not too high. Does anyone have a better explanation on what this white powder-like stuff is? How do I fix it?
-Pool guys say that trichlor makes the white go away because it "traps all the white stuff and makes it go down". Does that make sense? According to what I know, trichlor is not a clarifier, it just adds chlorine and cyanuric acid to water.
-Any recommendations? I want to optimize the use of reagents and manage the levels smartly in those pools, but I can't do it if when I use less trichlor and more calcium hypochlorite (To avoid CYA buildup), water turns white.
HELP! Please. I'm confused....
Thank you in advance for everyone's help.