Black (I think) Algae that will not go away

duraleigh

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It won't hurt to go to 16 ppm for your FC. Don't go any higher as you will start to get too far above the suggested guide line of 12.

There is no black/white level of FC where you pool will suddenly blow up if you exceed our guidelines but use some good common sense and stay close
 

drewh

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Oct 19, 2014
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Brisbane, QLD, Australia
It won't hurt to go to 16 ppm for your FC. Don't go any higher as you will start to get too far above the suggested guide line of 12.

There is no black/white level of FC where you pool will suddenly blow up if you exceed our guidelines but use some good common sense and stay close
Haha... don't want my pool blowing up ;)

Ok ta. I suppose more chlorine is better re algae but sticking as close to the guidelines as poss is best practice. Thanks duraleigh!
 

drewh

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Oct 19, 2014
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Brisbane, QLD, Australia
I'm planning on SLAMing my pool next weekend, in the meantime my FC has fallen down to 4, then 2, then 1 today (using TF-100 test kit). The CYA is about 25 now and conditions here are very, very hot - 35 degree days. Should I leave things as is - the pool is perfectly blue & looks good - or put a bit of liquid chlorine in to tide me over to next Sun and stop any algae blooms etc? I'd rather not raise my CYA till after the SLAMing.
 

jblizzle

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Re: Black (I think?) Algae that will not go away - any help appreciated!

You should have never let the FC drop below the minimum for your CYA level as listed in the FC/CYA chart in Pool School.
 

drewh

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Oct 19, 2014
101
Brisbane, QLD, Australia
The problems been Jason that I've not had a test kit before a few weeks ago. I'd take my water to the pool shop almost weekly last year and FC was always at least 8. This season it's way down at 1-2 but CYA is 25/30 and was prob 80 last year. So once I've slammed, I'll then look at adjusting CYA and test what FC results. Then I'll know if I need a new cell (which I may do) or just FC being lost due to sun. But want to keep CYA low while SLAMming.

You know the weirdest thing? Since scrubbing those two spots (which seemed to turn out to be plaster) there is zero of the strewn black algae around the pool - none at all, anywhere. Usually there is ALWAYS some that appears within days (as pics at start of this thread shows). Even with FC being 2 today when I tested it. Bizarre...
 

duraleigh

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You know the weirdest thing? Since scrubbing those two spots (which seemed to turn out to be plaster) there is zero of the strewn black algae around the pool - none at all, anywhere. Usually there is ALWAYS some that appears within days (as pics at start of this thread shows). Even with FC being 2 today when I tested it. Bizarre...
Looking at the pics, I don't think that you had black algae. Black algae has a different set of characteristics than you have posted.

Now that you can test, keeping your parameters where they need to be and keeping your pool clean should go a long way to a crystal clear pool.
 

drewh

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Oct 19, 2014
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Brisbane, QLD, Australia
Re: Black (I think?) Algae that will not go away - any help appreciated!

True I've just called it black algae because it was black in colour, but I know the actual black spot algae is very different. But whatever the algae is, it's literally been there day in day out, and reappeared within a day or two. Just extremely persistent. So odd none is present at all. The only incident that happened maybe 2 weeks ago - I switched the cell off to add salt, and because FC was quite low the pool went green. I then added FC to 10ppm till it cleared. But there was this algae back again after it. Anyway will SLAM from this weekend and see if it keeps up fingers crossed.
 

kcindc

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The CYA test is very sensitive to lighting conditions. Do the test in bright sunlight with your back to the sun, holding the tube at waist level. Trust your results and use the shock FC level of 12. If you are confident of your CYA, no reason to retest unless you replace a lot of water. During a SLAM, you only need to test FC and CC. The PH test is unreliable once your FC gets to 10.

Make sure that you brush the pool at least once a day with an algae brush which is metal. Brushing removes the algae's protective coating so that the chlorine can kill.

Also you should vacuum the pool daily. Any organic material, like leaves/branches, will consume chlorine and you want all of the chlorine to be used on algae.
 

jblizzle

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Re: Black (I think?) Algae that will not go away - any help appreciated!

I forgot you had a SWG, so the lower FC was probably ok ... just your CYA is below the chart for a SWG pool.
 

drewh

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Oct 19, 2014
101
Brisbane, QLD, Australia
The CYA test is very sensitive to lighting conditions. Do the test in bright sunlight with your back to the sun, holding the tube at waist level. Trust your results and use the shock FC level of 12. If you are confident of your CYA, no reason to retest unless you replace a lot of water. During a SLAM, you only need to test FC and CC. The PH test is unreliable once your FC gets to 10.

Make sure that you brush the pool at least once a day with an algae brush which is metal. Brushing removes the algae's protective coating so that the chlorine can kill.

Also you should vacuum the pool daily. Any organic material, like leaves/branches, will consume chlorine and you want all of the chlorine to be used on algae.
Thanks, I did it like that with the sun against my back so my shadow then covers the tube etc. Problem was how much should the dot be obscured, 100% completely or just enough where it's only slightly there? I won't retest again till after I've SLAMed and then will work out what level to have it at (as per table, but want to make sure cell is working ok before going too high).

I try to clean leaves & debris out often... not yet daily but getting there.
 

duraleigh

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Go to TFTestkits.net and view the video on the CYA test.

It is not precise in telling you how much "obscure" is on purpose.......the test itself is pretty subjective but after a little practice, it should be easy enough for you to get it within 10 ppm either way
 

drewh

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Oct 19, 2014
101
Brisbane, QLD, Australia
Thanks duraleigh, I did see that & all the videos re using the test kit. On that one liquid was squirted in until you definitely couldn't see the dot. Hence asking if that is the right condition or if the dot can just barely be seen if that's not far enough.

One quick important question. I'm thinking of starting the SLAM tomorrow. But my FC is staying quite low (1.5 today and tiny amounts of green algae showing). My CYA is 25 and here in Brisbane, Australia it's hot humid conditions, the most intense of the year or close to it. Should I raise my CYA to 40 and then SLAM? I know I'll use more chlorine then but given conditions if I SLAM with a CYA of 25 is quite a bit of the chlorine going to get killed off by the sun vs and algae etc? Ie fighting a losing battle against sun and algae. Thanks!
 

duraleigh

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Should I raise my CYA to 40 and then SLAM?
Forum consensus is to SLAM with CYA around 20 or so is ideal. There is no black and white, perfect answer but you won't go wrong with staying right where you are at 25 ppm.
 

drewh

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Oct 19, 2014
101
Brisbane, QLD, Australia
Re: Black (I think?) Algae that will not go away - any help appreciated!

Thanks Dave, that's exactly this info I need. Prob going to be hard to start before Mon after all but I think it'll be all systems go from then.
 

duraleigh

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It is a common "mistake" to try to SLAM either partially using your SWG or completely using it.....don't do it......it's problematic on several levels.

Turn off your SWG and SLAM using bleach. It may seem like a pain but your SLAM will be quicker and you'll get the test results you expect without surprises.

Follow that SLAM article to a T and don't do anything that is not in the article or leave out anything that is. :D
 

drewh

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Oct 19, 2014
101
Brisbane, QLD, Australia
Re: Black (I think?) Algae that will not go away - any help appreciated!

Yes I'll do that, use only bleach and keep the SWG off.

A potential unrelated issue is whether my cell needs replacing. Last season it was producing over 8 ppm FC but CYA was around 70/80. So the quite low FC levels now (in the mid 1's) could be because the CYA is low more than the cell packing up, especially in these very hot conditions we're having here. After I SLAM I'll look to lift the CYA level slowly in small steps and measure what happens to the FC level.

I will follow the article to a T ? already read it many times.
 

jblizzle

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With the lower CYA level and visible algae ... it is not surprising that the SWG is struggling to maintain a higher FC level. After the SLAM, and raising the CYA, odds are that your SWG will be working as expected.
 

drewh

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Oct 19, 2014
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Brisbane, QLD, Australia
Re: Black (I think?) Algae that will not go away - any help appreciated!

Ok ta Jason, only a tiny amount of green algae that was brushed away immediately but a good indicator of FC even before testing it.
 

jblizzle

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Re: Black (I think?) Algae that will not go away - any help appreciated!

Likely if there is a little algae visible on the surface, there is even more that is not visible in the water. The OCLT is a good tool to check if there is stuff in the water.