High pH and green water

twinmomma · Postby **twinmomma** » Mon 26 Jul, 2010 13:45

I have also posted this on the Pool Algae forum.

Please help, I am VERY frustrated. We have been battling High Ph for several weeks and the level is not decreasing. Our pool water is now green.

We had the water tested yesterday:
Temp - 84
CYA 151
Total Chlorine 6
Free Chlorine 6
pH 7.8
Total Alkalinity 130
Adj. Total Alkalinity 85
Total Hardness 219

OUt pH was 8.2 as of 7/22. We added 3.5 lbs of pH Decreaserand clean shock. On 7/24 we were told to add 2.5 lbs of pH decreaser and 3 lbs of clean shock. Yesterday we were told to add 4 lbs of decreaser and 2 lbs of SOS. Yesterday afternoon the water looked as if it had lost some of its green color. Today it is the greeenest it has been.

We have an 18,000 gallon above ground pool. Any advice you can give is greatly appreciated.

Thanks.

lbridges · Postby **lbridges** » Mon 26 Jul, 2010 14:48

I recommend you plug your numbers into the pool calculator.

Your CYA value at 151 means the FC will have to be much higher to kill off and then avoid algae in the future. Before adding more shock/chlorine to the pool make sure you're adding it in liquid bleach of 12% chlorinating liquid since Trichlor (tabs) and Dichlor both will keep raising the CYA number and continue to make it harder to avoid algae.

twinmomma · Postby **twinmomma** » Mon 26 Jul, 2010 16:51

Thanks for the reply. I'll try adding some liquid bleach.

I must say, I am confused because the pool store told me that I had to get my pH down before anything else will work and the decreaser has not been decreasing the pH. I thought about going out and buying some muriatic acid. They told me that while my pH was high the chlorine would not work. However, everything I am reading, if I understand it correctly, tells me that I need a high level of chlorine to kill the algae and get the water clear again. I am so confused.

I am going to try the pool caclulator. Thank you so much for directing me to it. This is our 2nd summer for the pool. Last summer we didn't have any issues but it was a cool summer. This summer has been HOT and I'm thinking that may be part of our problem.

Thanks again!

lbridges · Postby **lbridges** » Mon 26 Jul, 2010 17:20

First, I wouldn't trust the pool store. Many are poorly trained and nobody will care like you do.

I would guess a bit less than 1/2 gallon of muratic acid would take you down to the median pH values.

If your pH is 7.8 then that is at the high end of OK, but not dangerously so, and it's OK to add bleach or chlorinating liquid. More than a few people who use salt water pool equipment to generate chlorine safely keep their pH around 7.6 to 7.8.

Postby **chem geek** » Tue 27 Jul, 2010 00:16

If you are going to shock to high levels, it is better to get the pH down to 7.2 before adding the chlorine. Adding bleach or chlorinating liquid will raise the pH and at shock levels it does so quite a bit. For lowering the pH, Muriatic Acid won't add unnecessary sulfates that come with dry acid, but it is nasty stuff (the half-strength Muriatic Acid doesn't fume quite as much).

twinmomma · Postby **twinmomma** » Tue 27 Jul, 2010 07:26

Thanks Chem Geek.

Does it seem "normal" that I have added so much pH down and th pH is not decreasing?
Should I use the muriatic acid vs the dry acid?

I need to go and get a new read out today,I am hesitant to go back to the pool store.

The pool is still green this morning.

Postby **chem geek** » Tue 27 Jul, 2010 18:26

When the TA is on the high side, the pH will tend to rise due to carbon dioxide outgassing. Remember that shocking is not a one-time event -- it is a SUSTAINED high level of chlorine and you'll need to add chlorine frequently at first as the chlorine will get consumed killing algae. I recommend you read the Pool School, especially the article on Defeating Algae.

twinmomma · Postby **twinmomma** » Wed 28 Jul, 2010 19:38

Ok - yesterday I added 1 gal of Muriatic Acid and my pH was low this morning. We added a total of 9 gal of liquid bleach today and the water is still green this evening and my pH is around 7.5.

I hope to see an improvement in the water tomorrow. This is just so frustrating, last year was the 1st year for the pool and we had a very cool summer in Ohio and didn't get to use it much. This summer, we built a deck and the weather has been perfect. We haven't used the pool all week and have 3 weeks befroe school starts again! UGH!

Postby **chem geek** » Thu 29 Jul, 2010 01:46

As was noted in earlier posts in this thread, your high CYA level is going to make it much harder to kill off the algae as it will take a very high level of chlorine to do so. You will need to lower the CYA via a partial drain/refill anyway so if you did that you would need less chlorine to fight the algae. Just remember that the chlorine level will drop fairly quickly killing the algae. You would need a FAS-DPD chlorine test kit to be able to accurately test the high level of chlorine. Personally, I would have done the partial drain/refill first.

twinmomma · Postby **twinmomma** » Fri 30 Jul, 2010 15:13

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?

lbridges · 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 · 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 · 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

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.