Black Algae

Silva1181

Silver Supporter
Apr 9, 2019
100
Houston
I noticed some black spots on the plaster near the steps, scrapped it and it was green under the black so I assume it's black algae. Hopefully the weather improves today so I can tackle this quickly. I plan to brush/scrub. Before I raise the LC level in hopes of killing the algae, do I need to make sure my CYA, TA, PH are properly balanced as well, as I believe they may be off since I haven't checked in two weeks due to crazy work schedule.

I also want to clean the tile grout above the water line, one I kill the algae. I can't find regular bleach anywhere near me and would like to know if I can the liquid chlorine instead as long as I dilute it with water since I know it's stronger the regular household bleach.


thanks,
 

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
2,925
Tampa, FL
Yep, LC is just stronger bleach.

Check your numbers before you do anything else! Post here, please. You want CYA somewhat low, 30ish, so you don’t have to use huge amounts of LC during your SLAM (well, you may need a lot of LC, but you’d need even more if your CYA is high). You want your pH at 7.2.
 

Katodude

Silver Supporter
Aug 22, 2017
1,068
West Palm Beach/Florida
Yes, go ahead.

Also for black algae get a stainless steel brush and brush those spots frequently. I also pour LC right over the spots and let the higher concentration wash over the spots. The LC is slightly heavier than water and will spread across them. The extra jolt of LC seems to help.
 

Silva1181

Silver Supporter
Apr 9, 2019
100
Houston
Thanks. It looks like the affected areas appear to be clearing up. My FC was at 14 at 8 pm last night and at 14 at 7 am this, and it’s now 10 am and it’s 12.

My CYA is 30 so I am going to keep at 12 all day.

I also checked my CC yesterday and it was 0 which I believe is good.
 

Katodude

Silver Supporter
Aug 22, 2017
1,068
West Palm Beach/Florida
You want to keep brushing the affected area at least once a day. You can probably switch to a nylon brush so you dont damage your plaster. You will want to keep an elevated level of FC for a few weeks, not fully SLAM level but still higher than normal. Black algae is really hard to kill and you want to make sure it is eradicated
 

Katodude

Silver Supporter
Aug 22, 2017
1,068
West Palm Beach/Florida
Don’t worry about pH and other measurements. In fact dont even worry about CC until you think your SLAM is done. High CC is an indicator of bad things going on, but a CC of 0 does not mean bad things are not going on.

For black algae the most important thing is brushing. I actually use a mask and snorkel and get right down there and brush by hand to make sure its all gone. I have even used a bamboo bbq skewer to pick at the individual spots to make sure absolutely everything is gone.