Is this algae???

[JPhilip]

I am having a problem and I need help. This sounds like the place to get it!

My pool is a 5 yr old 25,000 gal saltwater liner pool. I have had problems with a "dirty" pool for several years but this year after a heavy storm I had VERY cloudy water which was cleared with about 8 gallons of bleach and a bunch of cal hypo over several days. The pool then looked clear but the "dirt" on the bottom picked up significantly. When I say dirt, the bottom of the pool appears clean, but brushing even lightly gives a poof of "dirt" everywhere. This dirt is too small for the dolphin to pick up and comes right back through the sand filter. About a month ago I saw the first picture with a growth on the shady part of the steps. This was a first. It was cleared with getting chlorine to 24 PPM and brushing, though I didnt measure combined chlorine or try and maintain that level. Since then the "dirt" has picked up substantially and will now cover the pool and clump in several days. There are certain spots where it always comes back first and appears to be a growth to me. Even in these areas it will "poof" with the lightest touch of the pool brush. To touch, it feels soft, not slimy at all. I do occassionally notice a grittiness on the horizontal surfaces of the steps, almost like tiny rocks. The remainder of the picks are the "dirt". This will cover the pool if left alone even at chlorine levels of 10ppm. I have also added 2 quarts of copper algicide (Bioguard Banish) and 1 quart of Bioguard backup. This did approximately nothing.

Just got my T100 kit and currently have the following values:

FC 8
CC 0
CYA 25 (had been raised to 60 when I opened early May, slowly falling)
Salt 3400
TA 80
PH 7.6 ish
Calcium 200 ish

I have reviewed the SLAM procedure and with my new kit can now do it correctly, but I really want to know what this is. I was thinking mustard algae but everyone I show the pics to says no. One other observation is the growth appears like a yellow or brown at low chlorine levels. When the levels go up it looks more light gray. I do think it is a growth because vacuuming to waste clears it but it comes right back. I can hold chlorine with the SWG but I am running at higher levels (60% and much higher filter flows) than my usual 20-40%

Thoughts?

PS. These pics look bad to me as posted. I can send the files if requested

 

[LFrankow]

Hello, Welcome to TFP
I would call the cya 30, lower the ph a tad to 7.4 ish, turn off the SWG, then SLAM it.
Once it passes the three criteria, I would then aim for a CYA level of 60-80 as recommended in Pool School - Water Balance for SWGs, raising the CYA after will help your SWG keep up a little better, but do it after as FC to SLAM at 30 is 12 FC SLAMing @ a CYA of 70 means your effective FC needs to be 28.
What kind of filter do you have? If it is a sand filter you could read up on Pool School - Add DE to a Sand Filter

 

[tim5055]

Hello, Welcome to TFP
I would call the cya 30, lower the ph a tad to 7.4 ish, turn off the SWG, then SLAM it.
Once it passes the three criteria, I would then aim for a CYA level of 60-80 as recommended in Pool School - Water Balance for SWGs, raising the CYA after will help your SWG keep up a little better, but do it after as FC to SLAM at 30 is 12 FC SLAMing @ a CYA of 70 means your effective FC needs to be 28.
What kind of filter do you have? If it is a sand filter you could read up on Pool School - Add DE to a Sand Filter

This is spot on great advice!


Jeffrey,

What has been happening is that you have never held the chlorine level high enough, long enough to eradicate the algae. You kill some of it (turns grey) but the colony is still there. When the chlorine level drops it starts growing again. When you vacuum to waste, you get a lot of it but any remaining algae continues to grow. Some types can double the colony size in as little as 4 - 6 hours, so if you don't get it all it comes back.

Follow the full SLAM Process procedure.

 

[JPhilip]

Do you think this is a mustard algae?

 

[tim5055]

Do you think this is a mustard algae?

Is that area of the pool in shade most of the time?

 

[LFrankow]

Well for sure it is algae, and even if it is mustard algae which it could very well be

Mustard algae tends to grow on the walls and floor of the pool on the shaded side

That quote from here. Pool School - Mustard Algae
Either way a SLAM is in order.

 

[JPhilip]

Yes, always

 

[tim5055]

Yes, always

Well, it could be but our solution is hte same - lots of liquid chlorine. If you suspect it's mustard there will be an additional step at the end of the SLAM Process, but not now.

 

[JPhilip]

Sorry to be such a bother, but what is the possible extra step, and how will I know if it is Mustard?

 

[LFrankow]

The link I posted in reply #6 answers both of those questions.

 

[SoCalGuy]

Extra step involves elevating FC to a "mustard algae level" (based on CYA) for a day. Some folks also pull their lights and brush out niches, which may sound like overkill, but the idea is to be extra thorough and make sure none is hiding anywhere to rebloom downstream.

 

[AimeeH]

Extra step involves pulling the lights and brushing out niches, which may sound like overkill, but the idea is to be extra thorough and make sure none is hiding anywhere to rebloom downstream.

Actually, while that is always a good thing to clean and double check, the final step in the SLAM process for mustard algae involves raising your chlorine to mustard shock level for 24 hours. Chlorine/CYA Chart

Also, making sure that anything that was in the pool previously is thoroughly washed and all pool toys also sanitized.

In all honesty, I think mustard algae isn't as common as people think. Most of what we see is regular old algae caused by chlorine dropping too low or not being maintained well enough for the CYA level.

 

[JPhilip]

So I am keeping pool at mustard level until the 3 components of the test are passed. If I am to work on the light, that means getting in the pool with very high chlorine. Is this safe? I also worry about my dolphin. Will it tolerate FC of 18 for a few hours to sanitize it?

 

[AimeeH]

So I am keeping pool at mustard level until the 3 components of the test are passed. If I am to work on the light, that means getting in the pool with very high chlorine. Is this safe? I also worry about my dolphin. Will it tolerate FC of 18 for a few hours to sanitize it?

You want to follow the SLAM process as detailed here until all three tests are passed. Pool School - SLAM - Shock Level And Maintain

It is safe to swim with FC up to shock level for your CYA. If you think you have mustard algae then once SLAM is complete (passing three tests.....clear water, CC less than 1 and OCLT of less than 1) then you can elevate to mustard shock level for your CYA for 24 hours. See Pool School - Mustard Algae

 

[JPhilip]

I have now completed (perhaps) my SLAM but probably not good enough. My details are attached, but basically held mustard shock levels for 4.5 days and passed the OCTT with clear water and CC of .5. I left for a long weekend and chlorine drifted down to 9 ppm. Repeat OCTT was a fail. I also did a water sample at pool store and they told me CYA was 50 but I had done all my calculations based on a the previously measured cya of 25 (both my reading and pool store). I guess regardless of which was right, I need to slam more, correct? Anyone see anything unusual in these numbers? All shock is 10%. There is still "dirt" on the bottom of pool though MUCH improved. No growth on the shady part of the steps, but there are discrete parts of the pool along liner seems that consistently get dirty before all other areas. They are the same ones as in the pictures. Pool was brushed 1-2/day during the slam

Initial Conditions: CYA 25 (my reading and pool store reading) PH 7.5 TA 80 Per chart: FC for Shock = 12 FC for Mustard Shock = 18 Date Time FC CC TC Notes 16-Jul 1:00 AM 7.5 0 7.5 Start slam. Add 3 gallons Shock 10:00 AM 20.5 0.5 21 4:00 PM 16.0 0.5 16.5 Add 1 gallon shock 7:00 PM 17.5 0 17.5 No add but SWG at 80% 17-Jul 8:00 AM 20.0 0 20 8:00 PM 18.0 0 18 SWG still 80% 18-Jul 6:15 AM 18.0 0 18 8:00 PM 18.0 0 18 SWG still 80% 19-Jul 6:15 AM 14.0 0 14 SWG down to 20%. Add 16 oz cal hypo (73%) 8:00 PM 13.5 0 13.5 Add 1 gallon shock 10:00 PM 18.5 0.5 19 SWG OFF for Overnight test 20-Jul 6:15 AM 17.0 0.5 17.5 Fail OCTT. SWG to 40% and add 1 quart Shock 8:00 PM 13.5 0 13.5 Add 5 quart shock 10:00 PM 18.5 0 18.5 SWG OFF for Overnight test 21-Jul 6:15 AM 18.0 0.5 18.5 PASS OCTT. Pool clear and CC acceptible. SWG to 60%, out of town for weekend 24-Jul 3:45 PM 13.5 0 13.5 SWG 60% since 7/21. Large amount of cloudy water coming from jets after pool vacuumed to waste 8:00 PM 11.5 0 11.5 SWG OFF for Overnight test 25-Jul 6:15 AM 9.0 0 9 Fail OCTT. SWG Back to 60% 12:00 PM 10.0 10 Pool store reading. CYA 50????

 

[JPhilip]

I rechecked CYA with my kit and it is 20-25 So I think the chlorine levels I have been using are adequate. The "dirt" on the bottom is definitely coming back rapidly, and in the traditional spots. Any advice?

 

[sccm_sysadmin]

I get that on the bottom of my pool as well, and it looks almost exactly like the photo you posted where the crud is building up next to a seam in the vinyl liner.

In my case, I really think it is just dirt that accumulates on a seam and there's not enough flow in that spot for the dirt to get over the 'hump' of the seam so it keeps building up. My pool is right next to a wooded area so I get all sorts of debris from that. I also don't have a pool robot that would clean it up regularly so it just builds up until I get a chance to manually vacuum it.

As for the stuff on the walls of your pool, I don't have any experience with that.

 

[Holydoc]

I rechecked CYA with my kit and it is 20-25 So I think the chlorine levels I have been using are adequate. The "dirt" on the bottom is definitely coming back rapidly, and in the traditional spots. Any advice?

When I underestimated my CYA level, my water did not have the sparkle and I started to get what looked like "dust bunnies" along the seams in my liner. I also noticed a little bit of algae, like yours, starting on my pool steps.

I refreshed my CYA Standard from TFTestkits and compared what I thought my CYA level was with the standard's results. I found out that I was underestimating my CYA (it was 60 not 40) and thus was not keeping enough chlorine in the pool. I SLAM'd the pool and kept up the SLAM until I was no longer getting "dust bunnies". My pool is back to crystal clear again.

I would recommend you purchase a CYA Standard from TFTestkits:

http://tftestkits.net/Standard-Solutions-c23/

and check your CYA levels after understanding exactly what the results should look like. I bet you will discover the same problem I had. Luckily it is an easy fix once you know the problems.

 

[JPhilip]

My result is from the TF test kit. Both readings I have done were 20-25. Pool store read 50. The dirt got much better with SLAM but did not go away. I dont think it is going to go away. My attention is turning to a fountain near (not connected) with the pool that is full of green algae. It looks different but could be constantly seeding my pool. This might be a role for an algaecide? Any thoughts on that?

 

[Holydoc]

My result is from the TF test kit. Both readings I have done were 20-25. Pool store read 50. The dirt got much better with SLAM but did not go away. I dont think it is going to go away. My attention is turning to a fountain near (not connected) with the pool that is full of green algae. It looks different but could be constantly seeding my pool. This might be a role for an algaecide? Any thoughts on that?

Jeff,

You misread what I meant. I know you are using the TF Test kit. However at the link I gave you, the company, TFTestkits.net, sells a CYA Standard that always tests with a result of CYA=50. Basically you can use this standard to tell exactly what the dot at the bottom of the CYA tester should look like once you reach your CYA level. When I tested, I was trying to get the dot to fully disappear like the directions say. However once I got the Standard, I found out that the dot was still visible for the Standard at CYA=50 and just obscured a bit. So I retested my pool water for CYA using the newly discovered "obscured Dot" and discovered I was off by 20ppm! I thought I was doing it right. Live and learn.

I am not saying that this is your problem. But your photos and recant of your story is so similar to my own, that I think you will find out you have the same problem.