Noob fighting black algae - please help!

[new2poolz]

Hi everyone - First off, thank you for all of the amazing info and tools offered by TFP. This is my first pool and start of 2nd season; and we were looking to wean off the pool company coming out to the house once per month. Your website has given me the info and confidence to do that, BUT now I'm in a bit of a jam

Last time the pool company was here, I noticed what looked like black algae (from reading previous posts: coin sized, slow growing & slow dying gray turning to black spots). I pointed it out to pool tech and he then added his magic "90 day killer/preventer" and the world was a happier place.

Fast forward a few days; and the product did nothing as the algae began to get blacker with the addition of new spots.

Here's what I think happened - My FC went from 5ppm (I tested it using Taylor K-2006) down to 1ppm in a matter of 2.5 days a few weeks ago just before the pool guy arrived. Despite adding some shock to pool (pre-BBB, I used a 4-in-1 shock from Clorox), I believe we caught it too late as the previous owners must have dealt with black algae before evidenced by some leftover chemicals in their pool closet.

I'm on day 5 of SLAMing, brushing 3x per day, and these stubborn spots won't budge. I was hoping that SLAMing with brushing was enough until I read about using Trichlor tabs and granular directly on the spots for BA vs green/mustard.

Here are my readings which I'm testing 2x per day for FC

FC: maintained at 20ppm every 8 hours (using 8.25% good ole bleach)
CYA: 45
PH: 7.6 (when I started SLAMing and 7.8 now which I read is likely inaccurate).
CH: 300
ALK: 120

I previously used trichlor pucks but switched to bleach recently and stocked up on Borax so I have it AFTER killing this BA. I'm all about the BBB over the pool company and magic additives.

So my long winded post comes down to this: Do I need the addition of trichlor to speed this up since it's black algae vs. green or mustard?
This AM was first time I passed the overnight chlorine loss test, water is crystal clear, EXCEPT for Black algae spots (roughly 12 small, individual spots).
We have a short pool season; and I can't use this beautiful pool due to 20ppm chlorine and need to kill/rid this BA Beast.

Thanks so much in advance and for all of your awesome stickies, tools, and advice -

Sincerely,

Chris

 

[new2poolz]

Hopefully signature appears this time...

sorry -

 

[tim5055]

Liquid chlorine during a SLAM is best. Trichlor, dichlor, CalHypo and bleach have the exact same active ingredient. The only difference is what they bring along with them.

Most Clorox shock products are Dichlor which add even more CYA than Trichlor, so I would probably assume your CYA level may be higher than you think. I would bump your shock level up to 24ppm FC and keep up with the SLAM.

Do not place a trichlor puck on the spots as they are highly acidic and can damage both plaster and vinyl.

 

[new2poolz]

Thank you for saving me from some damage! The only reason the CYA is low is that I had to re-fill the pool due to a leak in the light which dramatically lowered the CYA to 20 after refill. It's now at 45 due to using trichlor for just a few weeks. That has stopped; and I no longer use the trichlor puck feeder that the pool company installed (Pentair Rainbow 320 puck holder). Puck holder is empty and only using 8.25% bleach for SLAMing and moving forward.

Will bump it up to 24. Anything else I can do aside from maintaining the SLAM and brushing like a maniac?

One of the more senior folks on here mentioned using the puck holder made by Pentair to hold the puck for algae on the wall. If I understand what you're saying, then I need to just be patient, continue the course with FC up to 24 vs 20 and this will clear -- correct?

 

[tim5055]

POP is what it takes (Pool Owner Patience). Test and adjust.

You can probably return the Borax you stocked up on as few people ever need it. That is one of the reasons we try not to sat BBB anymore because folks start stocking up...

 

[new2poolz]

POP is what it takes (Pool Owner Patience). Test and adjust.

You can probably return the Borax you stocked up on as few people ever need it. That is one of the reasons we try not to sat BBB anymore because folks start stocking up...

Certainly trying to be patient. My biggest fear is that my patience will equate to not being able to use the pool until the end of the season. I realize it's too difficult to predict from pool to pool; however I can't help but wonder if this is going to be several days, weeks, or months before I "win". As you know, tons of bleach, BRUSHING, and elbow grease while no swimming allowed

 

[duraleigh]

Pool School - Black Algae I would suggest you read the Black Algae article in Pool School....it's pretty thorough.

I believe you can swim and treat for Black algae at the same time. Why do you think you can not?

 

[DaninFLA]

Certainly trying to be patient. My biggest fear is that my patience will equate to not being able to use the pool until the end of the season. I realize it's too difficult to predict from pool to pool; however I can't help but wonder if this is going to be several days, weeks, or months before I "win". As you know, tons of bleach, BRUSHING, and elbow grease while no swimming allowed

no reason to not be swimming. if you are good to go on other items, jump on in. your FC should be below SLAM value so you can swim. that will make it easier to brush as well. you can brush a lot harder when in the water than outside using a pole.

try using a stiffer/shorter hand held brush and scrub scrub scrub

 

[new2poolz]

Pool School - Black Algae I would suggest you read the Black Algae article in Pool School....it's pretty thorough.

I believe you can swim and treat for Black algae at the same time. Why do you think you can not?

I did read the very thorough killing black algae. This is where I'm confused - I thought that I needed to maintain the FC at shock levels until the algae was dead as part of the 3 criteria.

Am I reading into the "water is clear" criteria as requiring this to be free of black algae?

That's my reason for not swimming is a FC level of 20 and on its way to 24; however if I don't need to continue the SLAM and can jump in and scrub when FC is safe, then I will definitely do that. What is minimum 'safe' level of FC to enter pool as I'm @ 20ppm now?

THANK YOU!!!!!

 

[DaninFLA]

I did read the very thorough killing black algae. This is where I'm confused - I thought that I needed to maintain the FC at shock levels until the algae was dead as part of the 3 criteria.

Am I reading into the "water is clear" criteria as requiring this to be free of black algae?

That's my reason for not swimming is a FC level of 20 and on its way to 24; however if I don't need to continue the SLAM and can jump in and scrub when FC is safe, then I will definitely do that. What is minimum 'safe' level of FC to enter pool as I'm @ 20ppm now?

THANK YOU!!!!!

you can swim when your FC is higher than SLAM, just don't stay in for long and shower off after. also don't wear your fancy lime green speedo, since the higher FC can fade it. high chlorine is tough on fabrics. I have been in my pool at high FC values to remove the light, fix drain, etc. its ok. just don't stay in there for an hour swimming laps.

 

[new2poolz]

Thank you as well, Dan. I'd love to get in their ASAP and scrub with a small brush! I've been itching to put on my scuba gear and stay down there and scrub like a madman. All of my gear has been thoroughly cleaned so as not to transfer black algae from ocean to pool. Would this be okay or do I risk introducing something from my gear that I don't know about?

- - - Updated - - -

AWESOMENESS! Thank you although I'm bummed about not rocking my lime green speedo. :bowdown:

 

[new2poolz]

Liquid chlorine during a SLAM is best. Trichlor, dichlor, CalHypo and bleach have the exact same active ingredient. The only difference is what they bring along with them.

Most Clorox shock products are Dichlor which add even more CYA than Trichlor, so I would probably assume your CYA level may be higher than you think. I would bump your shock level up to 24ppm FC and keep up with the SLAM.

Do not place a trichlor puck on the spots as they are highly acidic and can damage both plaster and vinyl.

Tim,

Just so you know, I had tested CYA last week @ 45 and this was 3 days after discontinuing ANYTHING but bleach. To my surprise in testing today after your post, the residual CYA from 1 week ago+ drove it up from 45-60 for CYA.
Great call - can't believe the conditioner hung around that long despite my initial test results. I've referenced the CYA:FC chart for my new #'s of 8 FC and 24 shock.

 

[tim5055]

I did read the very thorough killing black algae. This is where I'm confused - I thought that I needed to maintain the FC at shock levels until the algae was dead as part of the 3 criteria.

Am I reading into the "water is clear" criteria as requiring this to be free of black algae?

That's my reason for not swimming is a FC level of 20 and on its way to 24; however if I don't need to continue the SLAM and can jump in and scrub when FC is safe, then I will definitely do that. What is minimum 'safe' level of FC to enter pool as I'm @ 20ppm now?

THANK YOU!!!!!

Two issues - Black algae and safe swimming

Black Algae - Keep your FC between the high end of normal and shock, so for you I'd say 10 - 24. You don;t have to hold shock, just stay in that range. Brush the spots you see a few times a day to break up the biofilm protecting the algae and allow the chlorine to do it's work. Look around for spots you may not see easily like light niches and bottom of ladders.

Safe Swimming - It is safe to swim when the FC is below your shock value. So, for you with CYA 60 up to FC 23 is safe to swim.

 

[new2poolz]

Thank you!

Two short questions - since my CYA jumped (45-60), my water level is a bit too high due to rain; i thought it would be more economical to drain approx 15-20% of water and replace to reduce the amount of bleach needed for the remainder of the season. This will put me closer to mid-40's CYA using pool math calculator.

1 - Does this make sense to save $$ in long run?

2- Is liquid bleach my only choice of sanitizer? My concern is if I'm going away for a week - in such case, can i toss a few pucks in OR should I beg a neighbor to add bleach daily/as needed? (Right now, in the NorthEast, it's pretty warm so chlorine demand is certainly rising towards its mid-summer peak)

 

[DaninFLA]

Thank you!

Two short questions - since my CYA jumped (45-60), my water level is a bit too high due to rain; i thought it would be more economical to drain approx 15-20% of water and replace to reduce the amount of bleach needed for the remainder of the season. This will put me closer to mid-40's CYA using pool math calculator.

1 - Does this make sense to save $$ in long run?

2- Is liquid bleach my only choice of sanitizer? My concern is if I'm going away for a week - in such case, can i toss a few pucks in OR should I beg a neighbor to add bleach daily/as needed? (Right now, in the NorthEast, it's pretty warm so chlorine demand is certainly rising towards its mid-summer peak)

I would drain the water like you said. your CYA isn't that high, but if you got it to 40 that would be good, and give you a little wiggle room. I would ask your neighbors to add the bleach. you can lower your water a little bit more and then use the pucks....but first, plug in the number of pucks to pool math to figure out how much it will raise your CYA and if that increase will be acceptable.

since you have already SLAM'd your pool and its running good, you should have an idea of how much FC you are losing per day? if you are gone 1 week, I would raise your FC up to near SLAM level, calculate how much FC you will lose in 3-4 days, then have your neighbors add more chlorine at that point, as you can calculate how many gallons to add at that point to get back up high. and then it would be 3 days till you got back to test as needed. better to keep it high and avoid time below your minimum I think. plus, its easier to have your neighbor come by one time and dump the already measured/set aside volume of chlorine once

 

[tim5055]

Dan has given good advice. I find 40 a bit too low for my CYA, but I'm a good bit further south and have full sun on the pool most of the day. While finding a neighbor to dump chlorine is the best idea, if you do go down to 40 you have the head room to use a floater and tabs while you are away.

 

[new2poolz]

I would drain the water like you said. your CYA isn't that high, but if you got it to 40 that would be good, and give you a little wiggle room. I would ask your neighbors to add the bleach. you can lower your water a little bit more and then use the pucks....but first, plug in the number of pucks to pool math to figure out how much it will raise your CYA and if that increase will be acceptable.

since you have already SLAM'd your pool and its running good, you should have an idea of how much FC you are losing per day? if you are gone 1 week, I would raise your FC up to near SLAM level, calculate how much FC you will lose in 3-4 days, then have your neighbors add more chlorine at that point, as you can calculate how many gallons to add at that point to get back up high. and then it would be 3 days till you got back to test as needed. better to keep it high and avoid time below your minimum I think. plus, its easier to have your neighbor come by one time and dump the already measured/set aside volume of chlorine once

Wow - you guys/gals are fast & rockstars - that's a brilliant method that would've taken me a few years to realize. Thanks for helping me use what I already knew (FC Loss) in order to avoid the pucks when possible OR use pool math. Why didn't I think of that....

Thank you, Dan & Tim.

 

[new2poolz]

OK - here's the latest update - black algae is now spreading.

Water looks crystal clear; however the black algae is beginning to spread with an additional 8 or 9 new spots about the size of a dime. Now I'm baffled since I've been maintaining FC above 24, brushing to exhaustion 3times per day, vacuuming, backwashing, passing OCLT, ....

I'm missing something here. I have the POP for original spots; but the new ones have me flustered, frustrated, and beginning to wonder what I could possibly be missing. Had a friend from the pool biz take a look today and he was baffled as well since the pool "looks" and "tests" well; but having an increase in spots.

Just brushed & vacuumed again hoping these new spots would come up, but .....nope.

Any ideas on new spots? I have not introduced anything new to the pool; i.e. people, equipment, floats, etc.

 

[new2poolz]

I've re-read Duraleigh's suggested Black Algae sticky for the 3rd time; and decided it's time for step #5 since I'm losing to the black algae with it having spread despite shock levels, brushing, vacuuming, backwash, etc.

Last evening, I used a certain pool company's "puck holder" that attaches securely (after some adjustments) to my pole. I secured one trichlor puck to the holder, then "scuffed" the black spots with the puck. I kept the scuffing time to roughly 20-30 seconds per spot to avoid any excessive plaster damage. This morning, I have noticed a 'lightening' of the spots which is encouraging and did not notice any discoloration other than the area being a bit whiter which I assume is a light removal of plaster which I'm comparing to using compound on a car's paint.

so my Plan of Action is:

continue brushing rigorously 3x per day
vacuum
backwash when I have a 25% increase in pressure
maintain FC between high normal and SLAM according to CYA:CHL chart
will repeat step #5 with "scuffing" of trichlor puck as needed following the Black Algae instructions provided
Do my best to remain patient and try to focus on the clean majority of the pool vs. the black dotted bully.

I will post results in case someone else comes across this menacing issue.

Thanks for the support and advise thus far.

Sincerely,
Chris

 

[new2poolz]

Ive given up on brushing these black spots and calling in a professional to analyze the plaster and determine:

a) exactly what the remaining spots are
b) if they can be removed via DIY methods

I was able to "kill" the larger black circles using step 5 of Killing Black Algae from Pool School, but the small ones aren't going anywhere. They have become lighter and turned almost a brownish color from being solid black; but they (and I) have hit a plateau so I believe it's time for outside help.

If there's any advice out there, I'd love to hear it since this is ALL new to me. Otherwise, I guess this thread will at least maintain a history for others if/when I solve the issue. I'll post results if I achieve them.