Black algae

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The addition of bleach only has the pH go up temporarily. As the chlorine gets used up, the pH drops back down. If this is not happening in your pool then your Total Alkalinity (TA) level is too high. A higher TA level causes carbon dioxide to outgas more quickly and that causes the pH to rise -- that is, TA is a SOURCE of rising pH itself. So you should probably just let the TA be lower after adding acid to get the pH to where you want. Don't add baking soda to raise the TA -- keep it lower (say, 70 ppm or even lower if necessary).

If you find that a lower TA has the pH be more stable, then you can always increase the Calcium Hardness (CH) to make the saturation index near zero if you have a plaster/gunite or fiberglass pool or have exposed grout in tile.
 
Re: Stains

It seems like at this time of the year, just like last year i got the rusty fading stains. Last year with the thought that it was black algae i brushed, shocked and after may they were gone. During spring this year right after the temperature in San Antonio started to rise and the oaks over my pool dropped their pollen the stains came back. I adjusted the chemicals as per your reccs and so on. They disappear with shock and circulation for 24 hours a day. I turned the pump back down to 23 hours per day and in the morning some are there. If I add bleach to the area close to the stains they disappear magically. I tried the vitamin C and they also go away. I am not sure if they are tannins or metal stains. I am convinced they r not BA. I am tempted to do an ascorbic acid treatment but if they r not metal it would be a waste. We enjoy the pool when it is easy to maintain with BBB but at this time it seems a lot of work. Any suggestions. My chemicals are pH 7.6, Cya 40, FC 5, TA 250. I use nothing but bleach and Muriatic acid for the most part. Water looks beautiful crystal clear. Help!!!
 
shock and vit c both work? That's odd. Did you test these things at the same time?
Describe to me how you determine this....

Retest your TA - wipe the tip of the dropper bottle in between each drop with a damp cloth. That seems awfully high and I'm wondering if it's the static build up problem.
 
Just retested, TA 140.
To be honest it seems like the chlorine worked faster. But the vitamin c tablet cleared it quite a bit (not immediately like bleach and not totally on a big stain).
Now it seems if I ran the pump 24 hours except for having to backwash more often does the trick. I have friends who look at me like a fool when I say that the pump does not need to be ran 24 hours a day. They do it all the time.
 
Ok, let me see if I understand what you are saying.
You notice the spots MORE when the pump doesn't run 24/7? If there are hours when the filter isn't running these spots are more pronounced? But you don't notice them as much as long as the pump runs nonstop?

If that's the case, it sounds organic - and when the pump isn't running you get FC "dead spots" which allow algae to get a localized foothold...
 
Not sure.
Can you give us more info on your pump?
shocking should take care of it. If you aren't finishing the shock process completely, if algae is present, lurking... that would explain why it's coming back when the pump isn't running nonstop.
 
Its a DE 48m2 filter. Im not sure if that is the info u need. Just checked the pool this morning. Looks great but pump ran all night. BTW i was thinking about adding Borax when I get the TA to 80 (I had never added Borax out of the BBB system). I shock with I gallon of 12% liquid shock which should bring the FC level to 12 based on the calculator. Appreciate any help. Thx.
 
Borates may help your situation :) -can't hurt.
Actually I need the pump info - the brand/model/speed etc. then we can tell approximately how much turnover of the water you are getting.
It doesn't sound like it's Black Algae.
It sounds like tannin. Black Algae wouldn't fade at shock levels without ALOT of elbow grease on your part.
Metal stains would not fade at shock level.
organic/tannin stains certainly behave as you are describing.
 

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Have some more info on the stains. Today i was able to take a good look at a few of them on a shallow part. They dont feel slimy but some have in the morning a dusty growth of about 5 mm that can just be picked up. It almost feels like wet rust, powdery. I smeared it on a white piece of paper and it is just "rust". I did an overnight FC test and it did not drop at all. Current numbers:
pH 7.6
TA 80
FC 20
cya 50
Even with this numbers and the pump running 24/7 there are a few appearing in. I tried Vitamin C test again today and it does have some effect.
I am thinking that if they appear even with such high TC it could not be BA. BTW a few weeks ago, thinking it was BA I added a copper containing algaecide therefore I assume the water does have some copper in it.
Should I try an ascorbic acid treatment?? never done it. Could it hurt?? Water looks really good. Help!!!
 
I can't tell if you have two things going on at once... vitamin C would work on a stain that doesn't brush away. If you can pick this substance up, then I assume it brushes away, correct? So what affect does the vit c have? You said "some effect", can you be more specific?

If you had no overnight loss, then this is not live, organic something consuming chlorine. If you can pick it up, then perhaps it's just some kind of dust or pollen. But Vit c would not have "some effect" on that situation.

Hold off on AA treatment - the diagnosis isn't conclusive...
 
I can pick on some of them a dust on top early in the morning while the water is still. But the stain is left behind. It can be brushed off with a bristle brush easily. If I put the vitamin C tablet on top (before I brush it) it does go away.Thx,
 
Hope u can see them. Thx
IMG_0475.jpg

IMG_0476.jpg
 
I would try spot treating them with Vitamin C tablets, if there aren't too many spots. Then just use the startup dose of sequesterant and if you see spots come back try adding a little more sequesterant and perhaps monthly doses.
 
I have been hesitant to add the vitamin c. However I did buy a Jack's magic ID kit and the stains disappeared with the #2 stuff (copper and scale). I thought about applying the powder for copper and scale from Jack's magic but I could not bypass heater therefore could not do it. I added the blue stuff and I am waiting for results. The next day there seem to be more stuff and the filter pressure increased suddenly. I assumed it was the metal chelator. Cleaned filter and I am waiting to see what happens. I did talk to some neighbors and they tell me they get the same type of stains after the pollen falls in the spring and in their experience it does go away in a few weeks. In conclusion I believe it is metal stains, probably copper that for some reason precipitates after the pollen season. I theorize that the pollen contains tannins which combine with metals and cause the stains. It is interesting that last year the same thing happened and after may it stopped being a problem. I am not sure if it is from all my hard work brushing and shocking or If I had kept the FC at "normal levels" they would have gone anyway. I guess I will keep my standard water balance per BBB, add a little bit of the blue stuff and see how it goes through the summer. We r enjoying the pool and ignoring the stains. Can I shock the pool while adding the blue stuff?
 

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