Grrr! Algae literally stuck to the bottom

[vwtoys]

I'm losing this battle with what appears to be very stubborn green algae that is stuck to the bottom of the plaster pool. I can brush some of it away but most of it is VERY VERY stubborn. A steel brush helps a little but it's also spreading everywhere. I came home from a month long vacation to find it's gotten much worse. It was being fed by tabs for a month.

In the center of the picture is after I brushed off what's loose on the bottom. Most of it is not coming off. The dark green stuff on the side is NOT coming off.
Prior to that I've been using store bought liquid chlorine. In the summer months it was mostly ok. But I noticed the green stuff getting more and more stubborn. Shocking it didn't get rid of the green stain last I tried, as you can see it's gotten very bad.

And the readings were:
CYA~60 (Probably more now since I used some tabs)
TA~160
pH adjusted

I'm in California and it's been very cold/rainy in the past month.

I need help to get rid of this stuff. What is it? Why doesn't it brush off?? HELP!!!

 

[Bama Rambler]

If you'll post a full set of test results we'll be better able to help you.

pH
FC
CC
TA = 160
CH
CYA

While CH & TA isn't really necessary it's good to know.

I suspect that your FC isn't nearly high enough and if you didn't shock high enough or long enough you really didn't help yourself.

 

[PoolGuyNJ]

As Dave/Bama says, get a complete set of results. Then be prepared to start adding liquid chlorine or bleach or if your CH isn't too high, Cal-Hypo .. Stop brushing the live algae or it will just spread more!

Algae lets go much easier after it's been dead for 12-24 hours. In fact, you will have better luck simply vacuuming it out once it get to that state.

Scott

 

[Richard320]

....
Shocking it didn't get rid of the green stain last I tried, as you can see it's gotten very bad.

And the readings were:
CYA~60 (Probably more now since I used some tabs)
TA~160
pH adjusted

I'm in California and it's been very cold/rainy in the past month.

I need help to get rid of this stuff. What is it? Why doesn't it brush off?? HELP!!!

Did you shock it by adding something one time? Shocking is a proces, not a product, and not a one-time thing. You really need a FAS-DPD chlorine test kit to measure the FC levels you have. Then dump a whole bunch of chlorine in, and retest and replenish until you're killing the algae faster than it can multiply. And then keep doing the same until it's all dead. Directions are in a sticky here.

 

[chem geek]

You posted about a problem with green stuff you could not brush off in this thread back in August of 2009. Have you been maintaining the FC level relative to the CYA level as described in Chlorine / CYA Chart? With a CYA of around 60 ppm (before the most recent Trichlor), you would have needed to have a minimum FC of at least 5 ppm in your manually dosed pool. The pucks probably didn't dissolve quickly enough to maintain that FC level. Note that the shock level at 60 ppm CYA is 24 ppm FC and needs to be maintained (i.e. not a one-time dose) until the algae is gone, the overnight FC drop is no more than 1 ppm, and the CC is no more than 0.5 ppm.

Also, do you have a TFTestkits TF-100 or Taylor K-2006 test kit? If not, then you really can't know what is going on with your pool -- the CYA test in particular is very inaccurate with test strips and with some pool store tests.

 

[vwtoys]

You posted about a problem with green stuff you could not brush off in this thread back in August of 2009. Have you been maintaining the FC level relative to the CYA level as described in Chlorine / CYA Chart? With a CYA of around 60 ppm (before the most recent Trichlor), you would have needed to have a minimum FC of at least 5 ppm in your manually dosed pool. The pucks probably didn't dissolve quickly enough to maintain that FC level. Note that the shock level at 60 ppm CYA is 24 ppm FC and needs to be maintained (i.e. not a one-time dose) until the algae is gone, the overnight FC drop is no more than 1 ppm, and the CC is no more than 0.5 ppm.

Also, do you have a TFTestkits TF-100 or Taylor K-2006 test kit? If not, then you really can't know what is going on with your pool -- the CYA test in particular is very inaccurate with test strips and with some pool store tests.

Yes, that problem eventually faded away. Now the problem is back and this time a lot worse. I'll be ordering a test kit this weekend. In the mean time, I'll try to get a reading from Leslie's store. They don't use strips for CYA test and I think it may be good enough info for you guys to help get me started this weekend?

 

[PoolGuyNJ]

Leslies will be fine. The only things we typically use strips for are borates and salt. Some iron but not often. Leslie's usually uses their OEM version of the Taylor K2006 test kit.

Things we need to know:

Gallons
pH
Alkalinity
Free Chlorine
Total or Combined Chlorine
CYA (aka Stabilizer)
Calcium Hardness
Water Temp (Cal-Hypo doesn't easily dissolve in cold water) You'll provide this.
Salt (Leslies give TDS, Subtract the salt).

Scott

 

[taekwondodo]

I recently had a pool that had algae embedded in the plaster - even when the overnight FC test said the superchlorination was done (FC overnight remained ~30ppm for several days), the algae was still there (it was a bank-owned home and crud had sat in the "bowl" of the deep end for months). I even tried scrubbing it with a wire brush - with no success.

After the superchlorination, I kept the FC between 2-3x min rec level (based on CYA#s) and over the course of 4-6 weeks it finally disappeared.

Once you get your test kit, Shock, and then stay on top of the FC and it will go away.

- Jeff

 

[vwtoys]

I'm back with some results, though not complete:

Gallons ~25000
pH 7.8
Alkalinity 90
Free Chlorine 0 (tabs in the pool but the low CYA might affect its effectiveness?)
Total or Combined Chlorine 0
CYA (aka Stabilizer) 20!
Calcium Hardness 200
Water Temp (Cal-Hypo doesn't easily dissolve in cold water) You'll provide this. ~ no thermometer on hand. Air temp is around 70ish the last few days, dipping into the 50s at night. So it must be somewhere in between.
Salt (Leslies give TDS, Subtract the salt). - Not recorded

First thing I did was dump 1/4 gallon of pool acid in to bring it closer to normal (Question: does acid go flat if stored? My bottle is a few months old.)
Leslie's guy said get the pH right, then adjust CYA, then shock.

Any suggestions?

 

[bk406]

Any suggestions?

Yes, chlroine, chlorine, and more chlorine. I wouldnt do anything else too your water chems. Do not add any more CYA until you're finished shocking. The pH is on the high side, but not out of range. You could lower it to 7.5 or so if you wanted, then you need to add bleach to shock the pool. I'm not sure I would trust the CYA number. If you have been using pucks, it's undoubtedly higher than 20 ppm. I'd add enough bleach to raise the FC to 25 ppm (based on a prior CYA reading of 60 ppm) and hold it there. The brush, brush, brush. Hold the FC at 25 until the pool clears and you lose less than 0.5 ppm FC overnight. Run the pump 24/7 until it clears.
As chem geek pointed out, you have had an algea problem in the past and you have never gotten hold of it. Unless you commit yourself to getting a proper test kit, do your own testing, and keep the FC in the correct range for your CYA, you will continue to have an algea problem.

 

[vwtoys]

The pucks have been used while I was gone for a month. I used about 6 3" tabs. How much CYA does that add?

In CA there has been a lot of rain while I was gone. It rained for 2 weeks straight and then kept coming back for another 2 weeks. So maybe some CYA overflowed out with the rain water. The test kit will be in sometime next week hopefully.

The water itself is very clear, just the bottom of the pool is riddled with stuck algae.

I'm going to the store to get 12 gallons of chlorine to prep for shocking. anything else?

 

[Prav]

Read Pool School, get educated, and listen/read a lot of what goes on here in the forum - you'll benefit by having a nice, sparkling, trouble-free pool without breaking the bank. :-D

 

[PoolGuyNJ]

Clorox or Great Value may be less costly. They are 6% vs Leslie's 12%. Many here use it.

After you have killed the algae, give it an additional 24 hours so it lets go of the wall and floor. Then vac to waste, working quickly to minimize lost water.

Scott

 

[vwtoys]

Locally our Orchard Supply Hardware (OSH) has 12% on sale for 5.00/2 gal. Regularly 6.99. I bought 6 packs and got a 10 off 30 coupon so I got 12 Gals for 23 bucks after tax. I think that's the cheapest I've gotten 12%. Hope this is enough to kill off the algae.

 

[duraleigh]

Hope this is enough to kill off the algae.

It may or may not be but it will simply grow right back until you start to keep residual chlorine in your pool.

While your treating your current algae issues, please take some time and read up in Pool School about the constant need for chlorine and the need to test your critical parameters much more frequently than you apparently have been doing.

You can get your pool crystal clear but it's going to take a few minutes mostly everyday if you want to keep it that way.

 

[vwtoys]

I have a question with keeping the CYA low (~20 as measured) and shocking, as suggested above. Wouldn't a low CYA allow Chlorine to be burned off easily by the sun? Shouldn't I get it back to 50ppm or more before shocking it so the Chlorine will stay in there longer? I know my last reading was closer to 60. But it rained so hard and it possibly washed out some water during this past month with the non-stop rain. So I'm not surprised if it's lower than 60.

Hope this is enough to kill off the algae.

It may or may not be but it will simply grow right back until you start to keep residual chlorine in your pool.

While your treating your current algae issues, please take some time and read up in Pool School about the constant need for chlorine and the need to test your critical parameters much more frequently than you apparently have been doing.

You can get your pool crystal clear but it's going to take a few minutes mostly everyday if you want to keep it that way.

I understand that. What I want to know is why this stuff is much harder to brush off than what I have been treating for in years past. I used to be able to clean off algae with a shocking treatment and vacuuming out the dead stuff.
Algae I used to get brush off pretty easily, but this stuff is very stubborn. As if there's something forming over it protecting it from the brush.

 

[chem geek]

I have a question with keeping the CYA low (~20 as measured) and shocking, as suggested above. Wouldn't a low CYA allow Chlorine to be burned off easily by the sun? Shouldn't I get it back to 50ppm or more before shocking it so the Chlorine will stay in there longer? I know my last reading was closer to 60. But it rained so hard and it possibly washed out some water during this past month with the non-stop rain. So I'm not surprised if it's lower than 60.

The shock level of chlorine is proportional to the CYA level so you need a lot more chlorine at the higher CYA level. Even with 20 ppm or so CYA, this will significantly protect chlorine compared to no CYA. Yes, you might lose perhaps half in a day this time of year (it's not peak summer), but you'll be using more chlorine than that at least initially getting rid of the algae (oxidizing the algae uses up chlorine). So it's a lot easier to keep the chlorine level up and hit the algae hard since the target FC level isn't so high. You can even go beyond the shock level -- hit it with 10 or 15 ppm FC if you like (since it's not a vinyl pool). If you really think the CYA level is truly 20 ppm and want to raise it to 30 ppm, then you could, but I wouldn't go to 50 ppm until you kill off all the algae and are done shocking. An easy way to add chlorine and to increase CYA is to use Dichlor, but don't overdo it. For every 10 ppm FC added by Dichlor, it will increase CYA by 9 ppm.

As for why this particular algae is sticking more, I don't know but it may be easier to remove after shocking since that tends to break down the chemicals that form a slime layer.

 

[vwtoys]

OK. Since I have no way to test high FC at this point. Should I wait till the kit comes in?

 

[chem geek]

You can dilute the test sample with tap water (test the tap water separately to get a rough idea of its chlorine content or better yet use distilled or filtered water if you have it) and use your existing test kit until the new one comes. It's probably better to not let the algae get ahead of you and keep attacking it with chlorine.

 

[vwtoys]

So in the last few days I have been keeping the pool with 15ppm or more of chlorine in the water. Keeping tabs of the chlorine level and adding chlorine every twelve hours or so. It is apparent that the bottom has cleared up a little. The stuff on the side is still pretty stubborn. I'll keep adding more and more chlorine to keep it at shock level. Right now I have added enough chlorine to get it up to 23ppm. In hopes that it'll have a stronger effect than the 15-18ppm that I had the last couple days.

I have a question. The chloramine readings is staying at .5 to 1ppm. Should I be concerned?