High pH and green water

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
lbridges
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High pH and green water

Postby lbridges » Sun 01 Aug, 2010 10:16

First, you probably need the FAS-DPD kit mentioned by Chem Geek.

Once you have that, you measure and hold the FC chlorine level at shock value until the FC value drops less than 0.5ppm overnight. That will tell you all the algae is dead and you can then let the FC fall until it reaches the correct maintenance level based on the CYA level.


phoys
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My Pool: 9m x 5m in ground, sand filter and bromine dispenser pump station.
Location: France

High pH and green water

Postby phoys » Sat 14 Aug, 2010 13:20

Interesting topic....nt
Did the usual Bromine and PH test on my pool yesterday - which was crystal clear - the clearest is has been all summer - I'd had a problem with a milky whilte suspension in the pool when I opened it which took me an age to get rid of - and so been keeping an eye on my pool... Once that went I then had PH + demand which would not go away and had just started to settle - ANYWAY - I DIGRESS..

Did the usual test after a couple of days of none use and the PH was very high as was the Bromine - and PH minus was required.

So I mixed the PH minus and threw it in the pool - DISASTER - the water went deep yellow as soon as the PH minus made contact with the water and there was a strong "chlorine" smell. As the water mixed the yellow colour went but left the water with a green tint - I was gutted - Tried looking up on the web what the issue was but the green colour always refers to Algae which I was pretty sure it wasnt - as it appeared instantaneously.

The weird thing was that the PH was looking more normal although the test dye did look slightly off colour

Anyway after 24 hours of deliberation I decided that despite the PH reading I would add PH +

The green tint disappeared as fast as it had arrived.

Not sure if you have heard of this before but I thought I'd share it with you and if anyone has had this before - or knows why it happened. I dont know if its "free" Bromine related but this is the first time that I have really worried about the pool water quality - I've had the pool for 4 years relatively trouble free.
Pete
phoys
Pool Newbie
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Posts: 3
Joined: Sat 14 Aug, 2010 13:06
My Pool: 9m x 5m in ground, sand filter and bromine dispenser pump station.
Location: France

High pH and green water

Postby phoys » Sat 14 Aug, 2010 13:27

Did the usual Bromine and PH test on my pool yesterday - which was crystal clear BUT after weeks of PH + demand my test kit suddenly was showing that the PH was very high as was the Bromine - SO I thought PH minus was required.

I mixed the PH minus and threw it in the pool - DISASTER - the water went deep yellow as soon as the PH minus made contact with the water and there was a strong "chlorine" smell. As the water mixed the yellow colour went but left the water with a green tint

The weird thing was that after I'd added the PH minus the PH reading was looking more normal although the test dye did look slightly off colour

I decided that despite the PH reading I would add PH + MY thinking being that PH varies so why not add the opposite of what caused the problem

The green tint disappeared as fast as it had arrived.

Not sure if you have heard of this before but I thought I'd share it with you and if anyone has had this before - or knows why it happened. I dont know if its "free" Bromine related but this is the first time that I have really worried about the pool water quality - I've had the pool for 4 years relatively trouble free.
The Bromine level was still reading high - but I've stopped putting any in until it subsides a little.

Pete
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High pH and green water

Postby chem geek » Sat 14 Aug, 2010 15:22

twinmomma wrote:Yippee - algae is gone. pH is low and holding. My water is now cloudy/milky. I added 2 lbs of shock and 2 clarifying tablets this morning. I'm not sure how long it will take to clear up. I'm wondering if I should add more shock?

You added shock? I certainly hope this was Cal-Hypo and NOT Dichlor (or powdered/granular Trichlor) because Dichlor and Trichlor will increase your CYA level which is definitely something you do NOT want to do. With Cal-Hypo, you increase Calcium Hardness (CH) which is probably OK if your pool is vinyl since the CH is probably low. However, why didn't you just use more chlorinating liquid or bleach? There is no such thing as "shock" in spite of what manufacturers call some of their chlorine products. Chlorine is chlorine is chlorine -- doesn't matter if it's used for regular chlorinating or for shocking which is nothing more than raising the Free Chlorine (FC) level to a higher level. Just slap a "shock" name on a chlorine product and charge more as it's now "special" -- yeah, right.

Please, please read the Pool School including the article on Defeating Algae . And do a partial drain/refill of your water to get your CYA lower. It won't go away by itself and will continue to cause problems unless you maintain a rather high FC level.

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