Help with algae?

#1
I have an inground pool that is 110,000 gallons and is ran by 2 Pentair VS pool pumps that run 24 hours a day 7 days a week. The PH is automatically controlled to keep the water at 7.4, My issue is I am constantly getting yellow algae on the walls even when my numbers are good. Any ideas why I get algae every week.

FC - 10
CC - .5
PH - 7.4
TA - 70
CYA - 35
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,305
NW Ohio
#2
Welcome to TFP!

Two quick questions before anything else:

1. Is that correct, 110,000 gallons?
2. Is this a public or private pool?
 

Flying Tivo

Well-known member
Jan 24, 2017
582
Monterrey, NL, Mexico
#7
Ginormous pool and would love pictures. Your first step is to let us know what Test Kit you are using. We usually relay on TFT-100 or K-2006c. Yellow algae usually means Mustard Algae, but im no expert and someonelse will chime in. Go to PoolSchool and start reading about SLAM and Mustar Algae. Your CC is telling us that there is something in your pool but we need to know which kit you are using to test.

Felipe
 
Mar 24, 2014
2,091
Greenville, SC
#8
The short answer is that there isn't enough chlorine to kill it. I am going to assume your test kit is a TF-100 or Taylor 2006(c), can you confirm?

How often and in what way is chlorine added to this pool? At what speed are the pumps run?
 
OP
OP
V
Apr 26, 2017
16
Needville, Texas
#9
I know how to slam the pool and I am going to do it but I need to determine why I got it in the first place while maintaining a FC of at least 9 ppm with a CYA of 30

- - - Updated - - -

The short answer is that there isn't enough chlorine to kill it. I am going to assume your test kit is a TF-100 or Taylor 2006(c), can you confirm?

How often and in what way is chlorine added to this pool? At what speed are the pumps run?
The test kit the TF-100 and the pool is chlorinated with trichlor tablets daily and I am using 21 tablets a week to maintain a 10ppm FC to try and prevent the algae but it doesn't work. One pump is running at 2700 rpms and the other at 2100 rmps.
 
OP
OP
V
Apr 26, 2017
16
Needville, Texas
#11
I just tested it yesterday and it was 30 maximum. The pool has an auto fill that is adjusted to a level right below the overflow drain so every time the pool is used which is a lot it loses water. Also both sand filters are backwashed weekly so I lose a lot of water there. Do you think it is a circulation issue?
 
Mar 24, 2014
2,091
Greenville, SC
#13
Even if you had terrible circulation, running FC that close to SLAM would make it difficult for algae to grow. I would be curious enough to use a pipette to get a water sample from near a wall that gets algae.

Do you brush the entire pool once a week? Some algae can develop a protective shell when they are attached to surfaces to shield from chlorine.

Also, I'm really curious. How do you have a gigantic pool that is used "a lot" and is also private. Seems like something is missing here :scratch:
 

Flying Tivo

Well-known member
Jan 24, 2017
582
Monterrey, NL, Mexico
#14
Even if you had terrible circulation, running FC that close to SLAM would make it difficult for algae to grow. I would be curious enough to use a pipette to get a water sample from near a wall that gets algae.

Do you brush the entire pool once a week? Some algae can develop a protective shell when they are attached to surfaces to shield from chlorine.

Also, I'm really curious. How do you have a gigantic pool that is used "a lot" and is also private. Seems like something is missing here :scratch:
Brady Bunch Perhaps???;)
 
OP
OP
V
Apr 26, 2017
16
Needville, Texas
#15
When was the last time you replaced the water on the pool?? If not this year your CYA is wrong or your test kit is old.

Felipe
The pool is only 3 months old and so is the test kit. I think they are both okay.

- - - Updated - - -

Even if you had terrible circulation, running FC that close to SLAM would make it difficult for algae to grow. I would be curious enough to use a pipette to get a water sample from near a wall that gets algae.

Do you brush the entire pool once a week? Some algae can develop a protective shell when they are attached to surfaces to shield from chlorine.

Also, I'm really curious. How do you have a gigantic pool that is used "a lot" and is also private. Seems like something is missing here :scratch:
The pool is brushed 3 times a week and the pool is used a lot because my kids and there friends are in it almost every day. There is nothing missing here.
 

Flying Tivo

Well-known member
Jan 24, 2017
582
Monterrey, NL, Mexico
#16
If the water was replaced 3 months ago the CYA seams in line. Please stop using Pucks as this will aggravate your CYA with time. Use Poolmath to get your numbers for Bleach. With a high usage pool you will have higher consumption on FC, so you probably have not kept up with usage. I would start a SLAM since your CYA is at a good spot for SLAM. Make sure your kids dont use the pool while Slamming, brush often and run your pumps all day.

Felipe
 
#17
With my drop test that I use and I don't have any pics.
Not to be skeptical but anyone with 110,000 gallon pool, has a couple of pics. You don't throw that kind of cash at your pool and then not take a couple of pictures. The biggest pool I've seen so far on this forum is about 40,000 gallons, so 3x as large.

Pics please. Because I would love to be wrong and see that one!

110,000 liters = 29,000 gallons
29k gallons is still a big pool
 
OP
OP
V
Apr 26, 2017
16
Needville, Texas
#18
If the water was replaced 3 months ago the CYA seams in line. Please stop using Pucks as this will aggravate your CYA with time. Use Poolmath to get your numbers for Bleach. With a high usage pool you will have higher consumption on FC, so you probably have not kept up with usage. I would start a SLAM since your CYA is at a good spot for SLAM. Make sure your kids dont use the pool while Slamming, brush often and run your pumps all day.

Felipe
The water wasn't replaced 3 months ago the pool was built 3 months ago. Like I said the pucks aren't an issue because the water is constantly leaving the pool out of the overflow. Using 21 tabs a week it handles the high usage. The FC is checked daily and is always between 7 - 10 ppm. Both pumps run 24 hours a day and never shut off. I maintained pools for a couple years so I know what the chems mean and how to do it. This is why I am asking for help because the FC readings vs the CYA levels say I should not be getting algae. I am thinking it is a circulation issue because you can look in anyone of the skimmers and you can't even tell the pumps are running.
 

Flying Tivo

Well-known member
Jan 24, 2017
582
Monterrey, NL, Mexico
#19
The water wasn't replaced 3 months ago the pool was built 3 months ago. Like I said the pucks aren't an issue because the water is constantly leaving the pool out of the overflow. Using 21 tabs a week it handles the high usage. The FC is checked daily and is always between 7 - 10 ppm. Both pumps run 24 hours a day and never shut off. I maintained pools for a couple years so I know what the chems mean and how to do it. This is why I am asking for help because the FC readings vs the CYA levels say I should not be getting algae. I am thinking it is a circulation issue because you can look in anyone of the skimmers and you can't even tell the pumps are running.
Please dont feel aggravated, we are trying to help. It seams you have old habits of maintaing pool according to pool stores. A new pool has to go through certain steps to open, not just adding pucks and swimming. I would highly suggest your read poolschool, its not that you dont know about pool, but you just dont know about the TFP method of maintaining a pool. Its a battle you wont win if you dont choose a method and stick with it.

With that level of FC there is no hurry, take it slow and read up.

Felipe
 
OP
OP
V
Apr 26, 2017
16
Needville, Texas
#20
Please dont feel aggravated, we are trying to help. It seams you have old habits of maintaing pool according to pool stores. A new pool has to go through certain steps to open, not just adding pucks and swimming. I would highly suggest your read poolschool, its not that you dont know about pool, but you just dont know about the TFP method of maintaining a pool. Its a battle you wont win if you dont choose a method and stick with it.

With that level of FC there is no hurry, take it slow and read up.

Felipe
I don't have bad habits from a pool store. I have never used one. I don't need to read pool school. I know how to start-up a new pool. I have done hundreds of start-ups for pool builders and maintained hundreds of pools a month when I owned my own pool service business. When they finish the pool and it is full they turn it over to me for the next month to balance the water and finish the plaster start-up. You have yet to give an answer to why the algae is forming at these levels. If you don't know then stay off my thread.