Algae Wars

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I think I was too quick with my verdict... :cry:

Today I noticed that the green stains were starting to spread at an alarming rate. I tried brushing some of it and there were once again clouds of green coming off the walls! Algae! :rant:

Water was clear.

Immediately got my TF100 and tested...

FC 8
CC 0
TC 8
TA 70
PH 7.4
CH 260
CYA 45

I'm currently in the "after shock" period, bringing the FC slowly down back to normal levels, so I know that I've not had low FC levels in the past 3-4 weeks. Been testing every 3 or 4 days (I have automated chlorine & acid dosing).

Anyway, I know what needs to be done, so I added Chlorine to get FC back up to around 20 and brushed the pool.

No decent rain recently... no high winds or dust storms... very little organic matter falling into the pool (no trees)..

Any ideas what brought the algae back? My thoughts are that I may not have completely killed it off last time... Can a tiny amount of algae really come back in force at these FC levels of around 8 (CYA 50)??? or is there something else that I'm missing?
 
Even though algae can't get started from scratch at normal FC levels, it can grow and spread if it is already there. Algae often forms bio-films on the walls of the pool that are protective layers that help it resist chlorine.

You need to check for hidden spots with poor circulation where the algae might have been hiding out during shocking and clean them out throughly while at shock level. Lighting niches are prime spots for algae to hide as are ladders and steps.
 
Thanks for the tip.

My pool lights have colored covers that attach over the top of them. I took them off and found that one of the lights had a heap of algae growing over it. Cleaned it out and hopefully there are no more sources. Only time will tell.

Thanks again.
 
Another update... 6 weeks on...

The algae wars continue. Over the last 6 weeks, I have had to shock 3 times. FC levels have been 4.0 minimum at all times, and I have been shocking up to 13/14 with pool filter running continuously. Typical test results over the last 6 weeks:

FC 4.0 (Minimum)
CC 0 (always)
TC 4.0 (Minimum)
TA 50-70
PH 7.5-7.6
CH 260
CYA 30

During shocking, I have been brushing everywhere daily like crazy (my wife thinks that my muscles on my arms look bigger now 8) ). I have also backwashed at least once towards the end of each shocking cycle. Shocking process has typically lasted at least 3 or 4 days. Pool water always looks crystal clear (except after brushing the first time). However once I set the pool pump back to normal timer operation (total 9 hours per day) and once the FC floats back to around 4-5, I start to get algae clinging onto the walls again.... I shock again and the cycle repeats itself...

This is driving me nuts. It seems that I'm just not getting all the algae. It is quite possible that I am missing "hard to get at" parts of the pool and that I'm not killing it all off. My other theory is that although I'm killing all the algae, I may not be getting rid of all the spores...

I'm about to shock even harder to about 19 and keep it there for at least 7 days... Your thoughts?
 
Daniel, Sounds like you have been doing all the right things, but the algae just doesn't want to go away!

Raising FC to 19 (MA shock level) seems reasonable.

Is there a possibility this is black algae? You did mention BA in your first post.

Try to keep the TA between 70 & 90.

Question to the forum: OP has a water feature (pic on 1st page of thread) that runs two times daily. Could there be a problem with the shock level not having enough time in the 'pot'/or inside of the water feature to kill algae?

Others will be along to chime in. Good luck & congrats on the new arm muscles! :lol:
 
I'm not convinced it's black algae... It just comes back too quickly and most of it brushes off fairly easily, generating small green plumes behind the brush..

By the way, the water feature runs with the pool filter. So, while shocking, the water feature runs 24x7. I would have thought that the feature should get enough exposure to the high levels of chlorine.
 
Further to my last post, I have now shocked to about 19, and brushed everywhere. Lots of green plumes behind the brush as it moves along the surface. Can still see a lot of dark staining.

From past experience these stains mostly go away after a couple of days at shock level. But, as mentioned in an earlier post, the stains do not entirely go away. These stains consist of green/brown patches in the bottom of the pool (particularly in the shady areas). Brushing does not appear to have much affect on them, but they definitely get much darker and larger once I start to see algae on the walls and floor in the sunny areas.

Maybe black algae? Don't know. I thought black algae produce dark spots. These are more like patches covering a few square feet of wall / floor...

I'm tempted to announce a prize (maybe a small toy Koala or something :wink: ) for the one who can help me say good riddance to algae once and for all :? ..
 
Daniel,

Send me the bear!! :lol: Keep your FC levels at shock until your pool is clear. Then keep your FC levels around 5-7ppm from that point forward.

NEVER let it dip below that level.................NEVER let it dip below that level.

Algae does not exist in a properly chlorinated pool. If you have algae, your pool has not been properly chlorinated.

My apologies for being so blunt but I am doing so simply to really emphasize my point. There are thousands and thousands and thousands of pools in the world that have no algae because they maintain adequate chlorine. Yours will do the same thing once you keep your chlorine up. :lol: :lol:

PS - your description would make me think it's mustard algae and not black algae.
 
I agree with Dave, Sounds like mustard. (Edit- I don't know where I got "Ted") End Edit

Dumb question, but confirm for me that you are doing the ole' "overnight FC" test before you decide to discontinue shocking? I know you said your typical treatment lasts 3-4 days... but perhaps you aren't shocking high enough, long enough...to kill the MA which requires higher levels for longer periods....see this link for MA levels.
 

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Guys,

Thanks for all the responses. I value your opinions and advice!

Dave, I'll go with your advice and assume we are dealing with MA. I'll go with 5ppm minimum and aim for around 6ppm from now on. (I too want to have one of the thousands of pools in the world that have no algae permanently or for long periods of time! Although the concept has been very foreign to me for more than 12 months now).

Poolmom, yes I have been doing the overnight FC test before discontinuing shocking. Most of the algae clears up within a couple of days, and then I have typically gone at least a couple more days at shock and then done the overnight FC test before drifting back to normal FC levels.

Joyce, we have only just come out of our winter. My current pool water temp is reaching around 28C (82F), thanks to solar heating and warm spring days. However, the problem has been persistent all through our winter this year, where the water temperature was typically around 13-16C (55-60F).
 
Sort of an aside, but I notice that your CYA was 45 in August, but 30 in October... You mention automatic chlorine and acid dosing... What are you chlorinating with? Are you SURE your FC is staying above the minimum recommended??

After I read auto-chlor, I thought that your CYA was going up up up, and causing the trouble. But it has gone DOWN....

You mention one backwash, but unless you backwashed out 1/3 of your pool volume, I would not expect to see that kind of drop...

just stirring the pot!
 
Yes, I have been observing CYA going down as well. The Rolachem dosing system is dosing 12.5% liquid chlorine (same stuff I'm shocking with), so no possible CYA source. The unit has been fairly reliable and I have tested at various times of the day. I am quite confident that the FC has remained above 4.0 (which is way above the minimum for green algae).

I have backwashed several times since August and that would account for some of the drop in CYA. I can only attribute the remaining CYA drop to the high chorine levels (due to shocking) that I have had over the last couple of months. Chemgeek posted an article about CYA dropping in high chlorine situations due to some sort of chemical reaction....

post71773.html

I believe that I'm seeing some of that CYA degradation going on. I'm not too worried yet, as I've just come from way too much CYA which caused me huge headaches!
 
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