Need help with green algae and possible tannin stains

[tcab]

I have mottled green stains on the sides of my pool that began cropping up a couple of days ago. I added bleach and have had my FC running between 26-30 for 24 hrs. My CYA is 60. I know that needs to be a little higher. My problem is that the green stuff is REALLY tough to brush off. I'm using a new metal brush that I just got from my pool store. (They don't carry algae brushes.) It comes off easily in places with a cheap hand held brush. Could the surface of my walls be so uneven that the metal brush isn't making good contact or have I not been shocking long enough? My water is clear.

Also, I have brown stains here and there on the bottom of my pool that I'm assuming are from leaves that sat for a few days when we were out of town. They haven't faded at all yet. Do tannin stains fade out gradually? I haven't tested my water for metal and I did use an algaecide once from my pool store before I found this site. My pool store did tell me that shocking wouldn't take care of organic stains. I kinda changed the subject.

Thanks in advance!.

 

[duraleigh]

Tannin stains from leaves disappear in time from my pool with constant adequate levels of chlorine. Your pool is masonry (mine's vinyl) so it may take longer.

Likewise, adequate levels of chlorine will eventually get rid of all imbedded algae. Constant brushing is need on some pools where chlorine has been inadequate for long periods of time. It is a tough job, but brushing, filtering and keeping chlorine high and constant will rid your pool of the stains and algae.

Posting a full set of test results will help us better judge your current conditions.

 

[tcab]

Sorry Dave, I knew better than that. Prior to shocking my numbers were as follows:
FC 3
CC 0
TC 3
pH 8.2 I added 2C muriatic acid per the pool calc.
TA 100
CH 320
CYA 60

How long should I continue to keep the FC elevated given the fact that I'm seeing green patches? I'll keep brushing, but I'm confused as to how diligent I need to be with shocking it if I may be looking at imbedded algae? Thanks again, Terry

 

[duraleigh]

How long should I continue to keep the FC elevated given the fact that I'm seeing green patches? I'll keep brushing, but I'm confused as to how diligent I need to be with shocking it if I may be looking at imbedded algae?

Hi, Terry,

I don't think it's necessary to shock the pool but, rather, simply elevate the chlorine above normal and keep it up there. I'd say brush the spots daily and run your FC up around 7-10ppm. You must keep it at those high levels until the stains have gone and it could take a few weeks.

Meanwhile, you've done nothing to your pool except elevate your chlorine. It's fine to swim and enjoy therest of the summer.

2 cups of muriatic seems very, very low to get your pH down into the mid 7's. What size pool do you have?

Why do you think your CYA needs to be increased....I'd think 60 is fine.

 

[tcab]

Hi again Dave,

You can't see, but I'm doing a happy dance this morning! With all of the threads I've read here on algae, I was afraid that I would have to use extreme methods to get rid of my problem. My pool is 30,0000 gal---we have teenage boys and a diving board was their biggest wish. Keeping my FC at 7-10 will be no problem, and I'll brush each day.

I thought that I needed to raise my CYA after reading the pool school page on water balance for SWG's. It recommends 70-80, possibly higher based on manufacturers recommendations. I'm going to run all of the TF 100 testa again today. Waterbear suggested that I wait a week before rechecking CYA because I added 12 lbs of stabilizer last Friday. My husband even commented that 2C of muriatic acid didn't sound like much to him.

We had a TERRIBLE pool school from our PB. I'm learning so much here and am very grateful for the quick responses from you guys. Have a great weekend, and thanks again.

Terry

 

[duraleigh]

Sorry I overlooked your pool size in your sig.

You may need very close to a gal of muriatic to get your pool down to 7.2ph

I'd test once more and add as much as a half gallon if your still at 8.2 You should see a drop in pH within 30 min with your pump running. Then maybe wait another 1/2 hour before adding anymore.

Do this very soon. 8.2 is not good for your pool.

 

[tcab]

2 QTS of acid and my PH is down to 7.2. Thanks once more...........