Advice - Algae alive or dead?

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NewHomeowner

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Jul 16, 2014
104
Westport, CT
Hi All. Am a recent joiner and am very grateful to all the folks on this board. I purchased my home last year and inherited the results and advice from the prior owner who had been "pool stored". Only until recently, after using trichlor pucks and cal-hypo shock for a year, did I realize that I could no longer keep my pool in control after a recent algae outbreak.

The pool never turned green, but I would shock the pool and come back to find green/yellow walls as soon as chlorine returned to normal levels. I learned that my >100 CYA pool had to be drained and I had ended up draining half the pool (much to the chagrin of my wife, who wanted me to just "hire someone"...). I would've drained more but was fearful of hydrostatic pressure as there is a high water table around here and there are no hydrostatic valves on my pool (48k gunite).

I'm using chemgeek's chart, and have been maintaining appropriate chlorine levels since refilling the pool.

My tests are as follows:

7/19 11am
FC: 15
CC: 0.5
CYA: 50
CH: 250
TA: 90
PH: 7.5

7/20 12am
FC: 11
CC: 0.5

7/20 8:20am
FC: 11
CC: 0.5

7/20 9:46pm
FC: 9.5
CC: 0.5

7/21 7:40pm
FC: 6.5
CC: 0.5


The water was clearing up real nice (turned green when I drained pool because pump couldn't run), and since I couldn't yet see the bottom to vacuum, I've been using the brush and swirling the algae around hoping that it would get suspended and taken in via the pump/skimmers.

I came home this evening, and the pool was very clear, but the walls and floor were very green/yellow. I never could figure out if I had mustard algae the first time around,... but am concerned this time.

My tests are coming up fine. The CC although at 0.5 seems within acceptable limits. I've passed the OCLT (I think),... Did I come back this evening to the dead algae that's been there the whole time or is this new growth?

I don't necessarily want to dump 9 bottles of 12.5% chlorine if the algae I just vacuumed up for the past 1.5 hours (Don't have separate vac, so using hose to skimmer, into DE filter) was already dead....

so 2 questions:

1. Should dead algae be white or can it be yellow/green?
2. Shall I go ahead and SLAM the pool or am I ok?,... I just scrubbed and the pool looks clean, other than a few spots I couldn't get go with my brush.

BTW, have a pool party this coming Saturday so would like eradicate any problems before then (Monday now :) so have some time)

Thank you all!!!
 
I am not an expert but from what I've seen it would be very rare to complete a SLAM in 48 hours–especially if you really have mustard algae! I suggest reading these two articles before you go any further: http://www.troublefreepool.com/content/126-defeating-algae ; http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shocking

BTW, did you use the PoolMath calculator to determine your SLAM level? I used your first test numbers and pool volume from your signature to come up with a SLAM FC at 20 and a mustard algae FC level of 29. I'd bring the FC up to mustard algae levels (29 ppm FC)–and hold it there–until there is no color change to your pool walls. Remember SLAM means Shock Level And Maintain. If you let the FC drift down before the algae are completely deceased, you will not be rid of them and you're wasting time. Buy LOTS of bleach and be prepared to test your FC often. Good Luck!
 
Thanks Tucsontico. Problem is that I don't know if I had mustard algae or just green algae. I had read all the articles in Pool School, and did keep FC at what I thought were adequate levels for green algae and mustard (not shock levels, just maintenance). It was on the walls, and had a yellowish greenish hue. It brushed off really easily the first time around, and now that its back, is the same.

Sorry, I did use pool math to get the 9 bottles of 12.5% bleach referenced above, which would get me to 29ppm FC. I was hoping that someone would just come and tell me that I don't have mustard algae (because its supposedly so rare, my CC: is good, and overnight chlorine levels are holding) and that the stuff I just vacuumed up was dead algae that's been there for the past week as I drained and refilled the pool.

Lastly, I just sucked everything into my DE filter. I probably ought to discharge it to the separation tank and recharge the DE so that it doesn't get back in the pool. My system is circular, so there is no waste line per se,... everything goes back into the pool (including from the separation tank).
 
Ahhh,.. I see your point. Per chemgeek's chart, I never initially added enough chlorine to stay at the 19.8 PPM FC shock level for even regular green algae... My CYA is really around 40-50 (subjective), so I thought the initial 15 or so was good enough... since those lower levels also get you ahead of the algae growth but just more slowly (referencing chart's footnote about impractical chlorine levels at high CYA).

Regardless, the water is clear now,... issue is just that I saw yellow on the floor and walls before vacuuming. Since the pool is now clean, I'd like to avoid SLAMing at 29ppm if the yellow algae I picked up was old dead algae and not new growth (again per my OLCT and CC)....
 
One more question,... say I move ahead with the mustard level SLAM (again, hoping someone chimes in and tells me otherwise),... that's a lot of reagent drops to test FC at 29PPM several times a day for consecutive days! Could I possibly do the test with 5ml instead of 10ml, and then count each drop as 1PPM instead of 0.5? Else, is it linear so that I can scale it down even more?
 
Since there was still visible algae, you aren't done with the normal SLAM yet. When it says "the water is clear" that assumes walls, steps, floor, too. Is the water clear after brushing? If no, then the water isn't clear. Dead algae will be grey.

When that is finished, then you go up to Mustard level. It's in this pool school article: http://www.troublefreepool.com/content/148-mustard-algae
 
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NewHomeowner said:
One more question,... say I move ahead with the mustard level SLAM (again, hoping someone chimes in and tells me otherwise),... that's a lot of reagent drops to test FC at 29PPM several times a day for consecutive days! Could I possibly do the test with 5ml instead of 10ml, and then count each drop as 1PPM instead of 0.5? Else, is it linear so that I can scale it down even more?
Click to expand...
Yes, a 5 ml sample size will have each drop count as 1 ppm and will save on reagent. I'm not sure you could easily scale down even more without introducing quite a lot more error.
 
Thank you all for your help, I really appreciate it. You were all correct, the algae is actually alive and well.

I took another overnight test. 13.5ppm Cl at midnight, 11.5ppm at 8am. Sigh... Hated doing it during the day (literally burning bleach, so should've started last night), but dumped 8 gallons down this morning. Have someone dropping by to add another gallon at 2pm, and will continue this evening and onwards.

The only problem I forsee is that I don't have a separate filter, so all the live algae I vacuumed yesterday is still sitting in my DE filter. It's a closed system, so I can empty the DE out into the separation tank and then recharge, but water still goes back into the pool after that from the separation tank. Hopefully, the SLAM levels of chlorine will make its way through the filter and kill what algae is lingering there as well?

FWIW, my wife keeps asking me why "everyone else's pool is just fine", and wants me to stop attempting this myself. I ran into a neighbor with a pool, and she told me that they spent close to $2,000 and about 2 weeks time to clear their last algae bloom (my son swam in their pool and I'm a bit suspicious that it may have been the original source of the mustard algae, because we don't have trees around our pool, hmmmm!). A further testament to how invaluable your collective advice here is. Thank you!
 

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NewHomeowner said:
Thank you all for your help, I really appreciate it. You were all correct, the algae is actually alive and well.

I took another overnight test. 13.5ppm Cl at midnight, 11.5ppm at 8am. Sigh... Hated doing it during the day (literally burning bleach, so should've started last night), but dumped 8 gallons down this morning. Have someone dropping by to add another gallon at 2pm, and will continue this evening and onwards.

The only problem I forsee is that I don't have a separate filter, so all the live algae I vacuumed yesterday is still sitting in my DE filter. It's a closed system, so I can empty the DE out into the separation tank and then recharge, but water still goes back into the pool after that from the separation tank. Hopefully, the SLAM levels of chlorine will make its way through the filter and kill what algae is lingering there as well?

FWIW, my wife keeps asking me why "everyone else's pool is just fine", and wants me to stop attempting this myself. I ran into a neighbor with a pool, and she told me that they spent close to $2,000 and about 2 weeks time to clear their last algae bloom (my son swam in their pool and I'm a bit suspicious that it may have been the original source of the mustard algae, because we don't have trees around our pool, hmmmm!). A further testament to how invaluable your collective advice here is. Thank you!
Click to expand...

If you follow the advice you are getting as close as humanly possible, your pool could be algae free by Saturday. Even with a 48,000 gallon pool, you won't spend one fourth of what your friends did to clear their $2000 algae bloom!

I gather you cannot "vacuum to waste" with your closed system. While I am not familiar with a closed-loop/separation tank system I believe that if the FC level in your pool water is at or above SLAM, the algae will die throughout the plumbing system as that water circulates through. Brushing the pool is also very important in the SLAM process. Also note that it is safe to swim in a pool that is has FC levels up to, and including, mustard algae level.

Open a can of POP (Pool Owner Patience) and keep SLAMmin'! Post pictures of your sparkling clear pool when able. :swim:
 
Thanks again. Here are some photos of the work in progress. I've thrown all the kids' swimming stuff into the 30ppm Cl pool to clean up. You can see that there's still a tinge of green at the very bottom of the deep end. Still "dusts" up when you sweep it. I don't know if I ought to try and vacuum up every last bit or try to stir it around and around until its white and dead.

View attachment 32111View attachment 32112
 
NewHomeowner said:
Thank you all for your help, I really appreciate it. You were all correct, the algae is actually alive and well.

I took another overnight test. 13.5ppm Cl at midnight, 11.5ppm at 8am. Sigh... Hated doing it during the day (literally burning bleach, so should've started last night), but dumped 8 gallons down this morning. Have someone dropping by to add another gallon at 2pm, and will continue this evening and onwards.
Click to expand...
Just so you know, chlorine loss does not necessarily mean the algae is alive. It just means that chlorine is getting consumed. Even when algae is killed, chlorine still continues to oxidize the now dead cells. Pretty much when you go from green to cloudy the algae is then dead and the rest of the time is filtering out the dead algae. The chlorine consumption is still higher than normal until the dead algae is removed, but at least the algae doesn't continue to grow during this period.

Brushing is an important component of the SLAM process because circulation is not perfect in a pool.

If your pool is clear and you have overnight chlorine loss and you haven't cleaned your filter, you can do so.
 
Thanks Chemgeek. Your advice and contributions are invaluable.

The water has always been clear, just keep getting some of this green/yellow dust so I've never really known if I had mustard algae. The entire pool gets plenty of sunlight all day, and I know mustard likes the shade, so it was always suspicious. Also, there are not any large trees near the pool and this isn't the time of year for pollen, so i'm stumped.

In any event, I hadn't backwashed my DE filters since vacuuming since the pressure remained the same at ~12psi. There is a separate debate elsewhere on TFP on whether keeping the DE filters dirty helps to further filter finer particles,... but that's probably a myth. Will backwash and recharge tomorrow evening after attempting one more vacuum. In the meantime, I might play it safe at 20-30ppm Cl until the weekend (expecting company).
 
Closed-loop system? So your backwash water goes to a DE separation tank and then that water goes back into your pool?!?!?

Eeeeeewe....from what I've seen come out in my backwash water, there is no way I want that water going back into my pool :eek:

Slightly kidding. Are you required to do that? Water too expensive?

Anyway, one item you might consider adding to your To Do list is to modify the plumbing so that you put a PVC Tee and spigot at the discharge from your pump but before the input to the DE filter. That way you can drain pool water if needed (and give the garden a good watering)



Sent from my iPhone using Tapatalk
 
Good thought @SunnyOptimism. Water isn't too bad, I hope, as I just refilled half my pool this week (was at 100ppm CYA last week).
There is no sewer here, just septic. The pool plumbing was probably set up this way as there is no where to put the water.

I would imagine that the water coming out of the unit would be clean, as it's after the DE filter. In any event, i'll try taking a photo of the equipment tomorrow. There is a "clean-out" line but I believe that comes from the pool (though i'm not sure from where).
 
chem geek said:
Yes, a 5 ml sample size will have each drop count as 1 ppm and will save on reagent. I'm not sure you could easily scale down even more without introducing quite a lot more error.
Click to expand...

Hmmm,... I think I may have been making a mistake when scaling to do a 5ml Cl test. Should I be using the same amount of R-0870 DPD powder? I've been taking a full scoop, same as usual, but am thinking I should be taking either half or double (not sure which way to go).

Took a larger than normal scoop yesterday night as I rinsed the scooper in the test tube, and what I thought was 30ppm Cl tested at 40ppm!! This morning's readings were at about 37, but then again, I used a smaller scoop.
 
SunnyOptimism said:
Anyway, one item you might consider adding to your To Do list is to modify the plumbing so that you put a PVC Tee and spigot at the discharge from your pump but before the input to the DE filter. That way you can drain pool water if needed (and give the garden a good watering)

@SunnyOptimism, here's a photo of the equipment. Sounds like this is not a common set up...
View attachment 32126
Click to expand...
 
I updated your photo, tell me if I got it right?



The yellow highlighted spot is where I would put a tee with a spigot so you can drain water when the pump is running.

Also, your setup isn't too unusual except for the fact that the separation tank is plumbed back into the pool. Some municipalities and cities do not allow DE filter owners to discharge spent DE because they consider it an airborne respiratory irritant in it's dried out powdery form. DE dust should definitely NOT be breathed in, but I don't agree that it has to be separated...but that's an argument with bureaucrats that I would definitely NOT win :) So therefore separation tanks are used and then the discharge water can be gotten rid of as needed (sewer or discharged onto property). Putting discharge water back into a pool would just seem to be a bad idea to me as you're just going to reintroduce particulates into your pool that were filtered out by the DE filter...

Can you tell me what some of those labels on the pipes say? I can't make it out.
 

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