Algae?

[PoolFun]

Third summer with the pool. A few strange issues this year (missing tiles, thrips, strange stains, algae?). I'll be posting in other topics, but want to get suggestions on the attached pictures. First set is obviously alage, but below the waterline, cleaned off easily and hasn't shown up anywhere else. The second set is in the deep end, does not brush off at all, had shown up shortly after I opened (I did the AA treatment at opening, late April), disappeared and then reappeared over the weekend. I noticed 2 or 3 spots Sunday evening and then today a bunch more (10 - 20) have shown up.

On Saturday:

FC: 2.5
CC: 0
pH: 7.3
TA: 65
CH: 310
CYA: 50 (2 weeks ago)
Temp: 74

OCLT last night 0.5, maybe 1.0 (3.0 -> 2.5 or 2.0); pH had crept up slightly to 7.4.

Water was clear when I first saw the algae, but has gotten cloudy the last day or two. I added extra liquid chlorine and MA tonight and will check clarity tomorrow. I have not had to go through the full shock process in the previous two summers and the water has remained clear and beautiful (most of the time).

My questions. Is the green algae 'mustard' algae and do I need to keep a close eye on those spots and look for other spots? What are the black spots? Best way to deal with them?

I did the AA treatment for metal stains when I opened the pool at the end of April. When I opened, the pH was above 8.4 and I think I have a calcium scaling issue (that is for another post). I've been hesitant to let the FC or pH get too high because of that. I have been adding sequestrant every week or so since April.

 

[PoolFun]

The Black Stains:

 

[PoolFun]

Just because I don't like being a downer all the time:


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Thanks for your thoughts and suggestions.

 

[Richard320]

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Run that pool up to shock level tonight (You'll lose less FC to sunlight that way)
Scrub that algae stuff with a steel brush (made for pools, don't use a paint stripper brush - trust me)

Those black streaks could be calcium, could be black algae, could just be marks from hitting the wall with the pool brush. What do they feel like?[/center:1dgnauff]

 

[Butterfly]

The streaks could be organic. Looks like something (like little junk from an oak tree) that the polaris ran over it and smeared a stain.

You can help confirm black algae if you can get a sample of the black round things (scrape some off w/your fingernail), and rub it on a heavy white paper (like business card). If it is green, it's algae. If it is round, black and becoming more numerous, it sure sounds like black algae.

As Richard said, it is important to have the right brush for the job:

Nylon is for vinyl, fiberglass, tile, and plaster that is less than one year. (Plaster includes any exposed aggregate and marcite finish, btw!) Combo brushes are for older plaster. All stainless are for algae (very stubborn green algae and also the ONLY brush for black algae.)

You CAN unscrew the Wall Whale from the nylon brush it comes with and screw it on a combo brush if your plaster is over a year old. Newer plaster is really too soft for anyting other than a nylon brush.

 

[PoolFun]

Looked this morning and the water was clear. I do have a steel brush, just purchased for apparent calcium staining, and it does not move them at all. Went for a swim this evening and tried to scrape it with my my finger nail. I could not feel it and it did not move or come loose. The smearing is not from "penny" (our Polaris), that is what they look like when they show up. I added another quart of Cl tonight and am checking OCLT. i'll report the results when I get them.

Also, last night it looked like a couple spots started to show up in the shallow end, but they have disappeared.

 

[PoolFun]

OCLT results: 4.0 last night, 4.0 this morning, CC: 0. Water is clear and sparkly. Seems like whatever it is, it is not organic.

 

[Butterfly]

Try crushing some cheap vitamin C tabs in a sock and holding it on the stain for a couple minutes and see if they lighten or disappear.

Also, last night it looked like a couple spots started to show up in the shallow end, but they have disappeared.

Now, that sounds like organic to me.

 

[PoolFun]

The spots seem to have faded slightly today, but are still noticeable. I did put some AA in a sock and held it against a couple of the spots for about five minutes. No change occurred. I am stumped.

 

[eripaulie]

I have cobalt stains in my fiberglass pool. Not sure if this is what you have or if your pool can get them but they look similar...There was a post in the "Chemistry 201" sub forum with pictures. I dont know how to put the link here but it is titled "Black Mystery Stains" on 06/20/12. Mine seem to be better with a lower stable ph and higher ch level.

 

[Butterfly]

I have cobalt stains in my fiberglass pool. Not sure if this is what you have or if your pool can get them but they look similar...There was a post in the "Chemistry 201" sub forum with pictures. I dont know how to put the link here but it is titled "Black Mystery Stains" on 06/20/12. Mine seem to be better with a lower stable ph and higher ch level.

Cobalt staining is common in FG pools. OP has a gunite/plaster pool. If you want, start your own thread and post your test results. We may have some comments/ideas for your pool

 

[Butterfly]

The spots seem to have faded slightly today, but are still noticeable. I did put some AA in a sock and held it against a couple of the spots for about five minutes. No change occurred. I am stumped.

Again, sounds organic. Exposure to chlorine lightens organic stains. Try rubbing a trichlor tab on the a spot.

 

[PoolFun]

Finally got a puck and sho'nuff, the stains disappeared. posting.php?mode=reply&f=11&t=64118&sid=9fc2d577476771a423663396ad962b4a#

I think what happened was that my filter was clogging up and, at the slower speeds I run the pump at, the pressure rise was not significant even though the flow was too low to kick the SWG on as much as I thought it was on. posting.php?mode=reply&f=11&t=64118&sid=9fc2d577476771a423663396ad962b4a#

So, I've back-washed and recharged the filter, verified the slower speeds are now enough flow to kick on the SWG, bumped up the %SWG and will continue with the liquid chlorine until this thing is under control. Now to deal with the calcium scaling.........