Algae is gone, now stains remain

[robl45]

Okay, so I finally got rid of the algae in the pool thanks to the kind people here. Now I have stains left. Some are dark rust stains around the steps and stuff, probably not rust, more like stains that happen from debris from the trees. Not quite sure how to treat these. The way I have treated them before is just to drop some chlorine granules in that spot. I dont' really want to do that though as it will add calcium to the pool, or if I use other stuff, it adds stabilizer. I have one of those stone things that I can try. Can't remember the name of it offhand.

The next stains are algae stains. the ones that are just like inground into the diamond brite. All the algae appears to be dead as the pool is sparkly clean and I see no more algae developing. How do I get rid of these stains? Most look like dirt ground in, some are greener.

 

[JasonLion]

Those sound like organic stains. Organic stains fade over time or after a couple of additional days of shock levels of chlorine. You might want to double check that they really are organic by treating a few small spots with granules. If the granules take care of the stains then shocking or time will take care of them.

 

[ivyleager]

Now I have stains left. Some are dark rust stains around the steps and stuff, probably not rust, more like stains that happen from debris from the trees. Not quite sure how to treat these.

Several days of maintaining adequate chlorine levels should take care of tannin stains from leaves and such. I had leaves accummulate on my steps for several days. Tannin stains developed, quite nasty. I did nothing but bump up the chlorine and circultate for 24/7 x 48 hours (probably more than enough circulation time, but I'm a circulation nut).

CaryB

 

[The Mermaid Queen]

You say some of the 'stains' are greener... perhaps the algae is not quite dead?
In either case (organic stains or residual algae) the solution is to keep your FC up a while longer... keep us posted!

 

[robl45]

I have noticed that algae seems to be returning. I am at a loss at this point. I have the SWG turned up from 10 hours to 12 hours on its highest setting. FC is sitting around 10 or so. It stays clear but over like a couple of weeks, I notice algae creeping in, does this mean I need to bring it way up with bleach again?

Assuming I"m using 1 gallon 5% bleach and the pool is 14000 gallons with 30 stabiizer. HOw many gallons will I need and how long do I leave it in for? Like do I get a case of 6 gallons and just put 2 in a day for 3 days or do I put in 6 gallons each day for a week or what?

 

[The Mermaid Queen]

I would shock with bleach per Jason's calculator linked in my signature. Plug in your numbers and get an FC value for shocking. Keep your FC at that level by testing and redosing with bleach often (twice a day or more often as practical)

30 seems very low CYA for an SWG pool... usually the SWG manufacturer recommends 70-90.

Are you testing your pool regularly? Having an SWG does not eliminate the need for good testing, just makes everyday chlorine addition easy. I suspect your FC is not where you think it is.

Remind us what test kit you are using (or what the pool store uses) and post your most recent numbers... CYA, FC, TC, pH, TA, Cal.

Merry Christmas!

 

[robl45]

according to the calculator, I will need approximately 3 gallons of bleach to bring the pool up by 12 FC. The pool is at 10FC now. So how long do I keep it up there for? Days, weeks or what?

I would shock with bleach per Jason's calculator linked in my signature. Plug in your numbers and get an FC value for shocking. Keep your FC at that level by testing and redosing with bleach often (twice a day or more often as practical)

30 seems very low CYA for an SWG pool... usually the SWG manufacturer recommends 70-90.

Are you testing your pool regularly? Having an SWG does not eliminate the need for good testing, just makes everyday chlorine addition easy. I suspect your FC is not where you think it is.

Remind us what test kit you are using (or what the pool store uses) and post your most recent numbers... CYA, FC, TC, pH, TA, Cal.

Merry Christmas!

 

[chem geek]

To recap, you reported that you had an algae problem after using pond water as your primary source (at least half) of the fill water and had an algea problem you were combating November 5th. You shocked with chlorine and the algae went away by December 9th. You had stains left and now report that the algae seems to be coming back on December 24th. At the time you were reporting the algae, it seemed like it might be mustard/yellow since it clung to the walls and was not green. Is it coming back in the same place on the walls? If so, then it might be black algae instead.

Mustard/yellow algae takes a higher chlorine level of 60% of the CYA level (vs. 40% of the CYA level for green algae) to kill effectively and you have to kill it on all surfaces that come in contact with the pool including brushes and poles. It can also be growing behind pool lights, in rail mounts, etc. If it is not all killed or otherwise gets reintroduced in small quantities, then it takes a higher level of chlorine of 15% of the CYA level to keep away (vs. 7.5% of the CYA level for green algae) though in your case you seem to already have the FC at 30% of the CYA with the algae growing (I suspect that the chlorine demand is high, but it's not as obvious because you're using the SWG).

Do you see a drop in chlorine levels overnight (with the SWG turned off during that time)? That is one way to know if you've got algae and that the chlorine is killing it.

It's possible that starting with pond water that the phosphate and nitrate nutrient levels were high to begin with so that the water is very conducive to algae growth, requiring higher levels of chlorine to keep it away.

I would shock at higher levels. If your CYA is really 30 ppm, I would shock at an FC of 18 ppm and would first lower the pH to 7.2 before adding the chlorine to get to that FC level.

Merry Xmas and Happy Holidays.

Richard

 

[robl45]

Yes, thyis sounds about right, I pretty much see the algae coming on the stairs a bit an din the crevices of the pool, I'd guess maybe theplaces that get less sunlight. I think it is either green or mustard alage, the stains were kinda grey in color I guess is best way to explain, but now are more greenish in color and I did see more algae growing along the wall closest to the house, the wall I can't normally see unless I'm walking around the pool.

I will check tomorrow morning before work to see if the chlorine level is the same or lower. Everyone mentions to shock the pool, but no one says how long to shock the pool for. Is it a week, 2 weeks, 2 days?

To recap, you reported that you had an algae problem after using pond water as your primary source (at least half) of the fill water and had an algea problem you were combating November 5th. You shocked with chlorine and the algae went away by December 9th. You had stains left and now report that the algae seems to be coming back on December 24th. At the time you were reporting the algae, it seemed like it might be mustard/yellow since it clung to the walls and was not green. Is it coming back in the same place on the walls? If so, then it might be black algae instead.

Mustard/yellow algae takes a higher chlorine level of 60% of the CYA level (vs. 40% of the CYA level for green algae) to kill effectively and you have to kill it on all surfaces that come in contact with the pool including brushes and poles. It can also be growing behind pool lights, in rail mounts, etc. If it is not all killed or otherwise gets reintroduced in small quantities, then it takes a higher level of chlorine of 15% of the CYA level to keep away (vs. 7.5% of the CYA level for green algae) though in your case you seem to already have the FC at 30% of the CYA with the algae growing (I suspect that the chlorine demand is high, but it's not as obvious because you're using the SWG).

Do you see a drop in chlorine levels overnight (with the SWG turned off during that time)? That is one way to know if you've got algae and that the chlorine is killing it.

It's possible that starting with pond water that the phosphate and nitrate nutrient levels were high to begin with so that the water is very conducive to algae growth, requiring higher levels of chlorine to keep it away.

I would shock at higher levels. If your CYA is really 30 ppm, I would shock at an FC of 18 ppm and would first lower the pH to 7.2 before adding the chlorine to get to that FC level.

Merry Xmas and Happy Holidays.

Richard

 

[chem geek]

I suspect the algae is growing where the circulation is poor so that the chlorine is getting used up locally and not replenished.

As for how long to shock, it is until the following 3 things occur: 1) no visible signs of algae remain (not even cloudy or dull water), 2) minimal (< 1 ppm) drop in Free Chlorine (FC) overnight drop, 3) minimal (< 0.5 ppm) Combined Chlorine (CC) measurement. In the case of mustard/yellow algae, I would add 2 more days of shocking beyond when these three criteria occur.

You should also make sure you don't just have pollen instead of algae. There are other threads on this forum that talk about that, including looking at the substance in a microscope, seeing if it grows in a bucket covered with a cloth (that still lets sunlight through) that keeps out pollen dust.

Richard

 

[robl45]

see thats the thing, my water is crystal clear. Yet people say I still have algae because some of it will not brush off, it seems stained to the side. But the water is not dull or cloudy or anything.

 

[JasonLion]

There are different kinds of algae. Some kinds grow floating in the water, some only grow on surfaces, and some grow both ways. That is part of why there are three done shocking criteria that must all be satisfied before you stop shocking, to take care of covering all the possible kinds of algae (and other situations).

 

[robl45]

so I was brushing a little bit earlier. They look like green stains. I brush and some comes off, but then stuff below is definately stained on and will not brush off. So do I just keep shocking until its gone?

 

[JasonLion]

Yep, you keep the FC at shock levels and brush the stained areas at least once a day, preferably more often than that. After a couple of days the stains should go away and you can stop shocking the pool.

 

[robl45]

I brushed again today, stains aren't really going away, but I will keep shocking.

 

[ivyleager]

I brushed again today, stains aren't really going away, but I will keep shocking.

What are your numbers?

I can't say enough about the need for a GOOD drop based water testing kit. I used mine daily for pH & chlorine, and weekly for everything else. I did that for 2 years. You learn so much about YOUR pool water. I'm sure my pool conditions are totally different than anyone elses. I learned that my pool needs a higher CYA (70-90) or it just sucks down my bleach on a daily basis.

You also learn how best to combat an algae problem. By running numbers daily at a MINIMUM, you know if the pool is sucking down the chlorine....sure sign that you've still got something eating it up. Ergo, continue shocking. If it holds, then something else may be going on or the chlorine level has not gotten high enough. Or the circulation is ineffective....may need increased running time, or the jets may need to be repositioned.

By doing the testing yourself, you get more reliable results than running around to 2 different pool stores.

FWIW, my first algae problem I overshocked and went up to about 30ppm in chlorine (5 gals of 12% at once w/ a pool volume of 24K). My liner did not fade at all.

My advice, get a test kit. Run your filter for longer time, maybe even 24/7 for a day or two. Keep at shock level and see if that helps. Post new numbers.

CaryB
Go Canes! (god we suck!)

 

[duraleigh]

I have watched this thread from the beginning and am glad Ivyleaguer finally has come up with what I have been wanting to say. I wanted you to hear it from someone else first because of my conflict of interest.

You are simply guessing at your problem. In turn, we are simply guessing along with you. Whether it's mine or the Taylor K-2006, you really need a test kit to fix your pool water issues.

Cary's advice is the best advice you'll get and the test kit will be the best money you'll spend.

 

[robl45]

yea, I know I"m working on the test kit. I did have the water tested about a month ago and the results were almost identical to th strips I'm using.

 

[robl45]

well I dumped 6 gallons of 5% bleach into the pool over the past 3 days, 2 gallons a day along with the SWG running twice as long as normal and the stains aren't even budging

I know there is plenty of chlorine in there and I suppose it could maybe use a little more stabilizer although the chlorine is not depleting overnight. Can I get a test kit from walmart, will that suffice?

I noticed on another thread that the pool is supposed to be around 80 degree temperature for the tests. I keep my pool around 86 degrees, does that make a difference?

 

[Guest]

The testkit that walmart used to sell was the Aquachem 6 way (at least in my area). Chemtura (Aquachem's parent complany) is not longer making this kit because they had too much trouble getting the reagents. I know this because I spoke with them on the phone. Seriously, your best bet is either a TF100 or a Taylor K-2006 test kit. When you consider how much your pool cost the amount you pay for the test kit is really a small price to know that your water is balanced and problem free. If you order the TF100 you will have it in just a few days! There are other inexpensive test kits you can get but none of them are going to allow you to test your FC at the high levels needed for shocking and killing algae!

When you are killing algae you need to test at least a few times a day since the algae will quickly start consuming the chlorine!
Strips just ain't gonna do it for you! If you rely on strips you are just spinning your wheels as evidenced by all the problems you have had in what was really a very simple problem that should have been handled in a few days at most IF you had accurate numbers on your water balance. Also with a SWG algae will often become evident on the pool walls and not in the water because the chlorine concentration in the cell is high and that is often enough to kill the free floating algae but the level in the pool is low (particularly with too low a CYA as you reported) which can create pockets of unchlorinated water that allow algae to grow on surfaces.

My two cents (and I help people clear green pools at the time at work so I do have a bit of experience in the matter).