Why would one suddenly have an algae problem after a few years?

[squirk]

Our pool is about four years old. Gunite, 16.5K gallons, Nature2. We live in southern Louisiana.

We live on a heavily-wooded lot, with a lot of pine needles falling into the pool. However, up until about a year ago, so long as I performed the proper maintenance as scheduled, I never had any algae in the pool and I never had to brush. However, over the last year or so, I am getting green algae in the corners and on some of the walls, and I now need to brush on a weekly basis.

I have always kept the skimmers and cleaner bag empty, I test the water every two weeks, I change the mineral cartridge every six months and check the chlorine tabs every week. I remove the cartridge filters and spray them out every six moths as well. My maintenance routine has not changed, so I can't figure out why I am getting algae now, after all this these years with no problems.

I know there are probably a ton of variables that could explain the issue, but I was wondering if there were some "usual suspects" when an algae problem like this suddenly appears after several years?

Thank you!

 

[kimkats]

Can you please run a full set of tests and let us know what test kit you are using. That info will help us help you. I have a couple of ideas but need more info.

Kim

 

[squirk]

Will do. I always have my local pool place test for me, as I am color-blind and have a hard time reading the strips.

Can you please run a full set of tests and let us know what test kit you are using. That info will help us help you. I have a couple of ideas but need more info.

Kim

 

[kimkats]

I think we may have found the problem We have found over and over again that pool stores do not do a good job with their testing. If they do the drop test they tend to hurry and some of the tests do not go as high or low as needed. The most important test I need you to do is the CYA test and this is the one they get wrong the most.

Even if you are color blind you should be able to do the test with one of our recommended tests kits. The PH test you will just look for the shades of color and find the one that matches. The others you will look for the color to change. Look in my siggy for the test I think is the best bang for the buck.

Oh and we can the test strips "guess strips" because it is really just a guess which level each thing is at.

I am guessing your CYA is getting high and your FC cannot keep up. The nature 2 could also be a problem in that it adds stuff not needed or wanted to the water (metals).

Let me know what you think about this info and we will go from there.

Kim

 

[Kiss4aFrog]

The chlorine tabs are adding both chlorine and CYA. The CYA helps protect the chlorine from oxidizing away too fast but it's cumulative. The higher your CYA level gets the more ppm of chlorine you need in your pool to do the same amount of cleaning.

The mineral systems, including a Nature2 are also a thing we're not very hot on. Most of us go with either a SWCG (salt water chlorine generator) or liquid bleach to sanatize our pools and keep algae from forming. It's simple and using liquid chlorine over tablets and pool store stuff is much cheaper with better results and cleaner, clearer water. You should also test daily or at least evey few days to maintain a proper ratio of chlorine (FC) to your CYA. - - > Pool School - Chlorine / CYA Chart

My guess would be your CYA is really high. Being in Southern Louisiana I'm guessing you'd want 40-50 ppm CYA if you're in full sun. If your heavily wooded includes shade to the pool than maybe 30-40.

How many hours a day are you running the pump ??

 

[squirk]

I think we may have found the problem :-( We have found over and over again that pool stores do not do a good job with their testing. If they do the drop test they tend to hurry and some of the tests do not go as high or low as needed. The most important test I need you to do is the CYA test and this is the one they get wrong the most.

Even if you are color blind you should be able to do the test with one of our recommended tests kits. The PH test you will just look for the shades of color and find the one that matches. The others you will look for the color to change. Look in my siggy for the test I think is the best bang for the buck.

Oh and we can the test strips "guess strips" because it is really just a guess which level each thing is at.

I am guessing your CYA is getting high and your FC cannot keep up. The nature 2 could also be a problem in that it adds stuff not needed or wanted to the water (metals).

Let me know what you think about this info and we will go from there.

Kim

I'll give it a shot and report back. Thank you!

The chlorine tabs are adding both chlorine and CYA. The CYA helps protect the chlorine from oxidizing away too fast but it's cumulative. The higher your CYA level gets the more ppm of chlorine you need in your pool to do the same amount of cleaning.

The mineral systems, including a Nature2 are also a thing we're not very hot on. Most of us go with either a SWCG (salt water chlorine generator) or liquid bleach to sanatize our pools and keep algae from forming. It's simple and using liquid chlorine over tablets and pool store stuff is much cheaper with better results and cleaner, clearer water. You should also test daily or at least ever few days to maintain a proper ratio of chlorine (FC) to your CYA. - - > Pool School - Chlorine / CYA Chart

My guess would be your CYA is really high. Being in Southern Louisiana I'm guessing you'd want 40-50 ppm CYA if you're in full sun. If your heavily wooded includes shade to the pool than maybe 30-40.

How many hours a day are you running the pump ??

Well, the Nature2 is a done deal. It's what my builder puts in his new pools by default, and back then, I didn't know much about the pros and cons of each type of system to argue with him. Changing up the sanitation system is a non-starter at the moment, so I guess I have to work with what I got.

I am running the pump about 10-12 hours per day currently.

I guess my original question remains, though - why would the problem start now, when I've been using the same equipment, same supplies, same maintenance schedule the entire time?

Thank you for the replyi!

 

[kimkats]

The nature 2 is adding CYA to your pool. Once your CYA gets too high your FC cannot keep up which leads to algae. It will only get worse. The only way to lower CYA is the remove and replace some of your water.

Did you know you can (and should) use liquid chlorine in place of the nature 2?

Kim

 

[squirk]

The nature 2 is adding CYA to your pool. Once your CYA gets too high your FC cannot keep up which leads to algae. It will only get worse. The only way to lower CYA is the remove and replace some of your water.

Did you know you can (and should) use liquid chlorine in place of the nature 2?

Kim

But why now? Why all of a sudden after three years would the CYA of the Nature2 be too high for the FC to keep up?

 

[kimkats]

Because every puck/tablet and pack of powder chlorine you put in adds CYA. For every 1 ppm of chlorine you add with pucks, you add 0.6 ppm of CYA. It adds up over time. The only way to remove CYA is to remove the high CYA water and replace it with new water. A little CYA is needed but too much will cause the problems you are seeing now.

You got a good run out of it. We see if all of the time. After 2 or 3 years a pool owner will start seeing algae. They say the same thing "but is had been fine until now".

 

[Mr Bruce]

Because at a higher CYA the FC also has to be higher to be effective. The tabs are constantly adding CYA, it doesn't go away without water replacement. The Nature 2 needs to go as well, metals in pool water is a giant "no-no".

The best thing you can do for your pool is a proper test kit. From there you can figure out exactly where you are and what you need to do next. Other than that, there isn't much to do other than to pull the tabs, take out the mineral thing, add a gallon of bleach every day with the pump running and fill out your signature

Lastly, the "location" field is not be nosy but to help with common regional variables in water quality, daily sunlight and swim season. A proper one would be helpful

 

[squirk]

Interesting information. Thanks to you both.

Dumping a gallon of bleach into the pool every day is not in the cards. I travel a fair bit, and I need a more automated solution. Maybe I need to investigate upgrading to a SWCG? I have no idea.

 

[yann]

HI

The automation solution (SWG) is a great idea, but first you need to fix your algae problem.
And the only way to do that is to get yourself one of the recommended test kits (TF-100 or Taylor K2006C) and then follow the SLAM Process procedure.
It may take days or weeks to clear your pool, and it's a daily thing, even hourly for the first day or 2.

Good luck

 

[squirk]

So, to make sure I understand this properly:

1.) Excess CYA is added to the pool with every tab.
2.) CYA in proper amounts is good because it prevents the chlorine from burning off in direct strong sunlight.
3.) Too much CYA will prevent the chlorine from burning off, but will also prevent the chlorine from properly sanitizing.
4.) In the Deep South (U.S.), with the pool receiving a lot of direct sunlight, I should be shooting for a CYA/FC combo of around 50/7.

Is that right?

 

[Mr Bruce]

That is pretty much it!

At the risk of being tediously redundant, the other very important take-aways are that a) metals are bad in your pool and b) there is no testing like your own with a proper test.

 

[kimkats]

The only tweak I would do is

1. Excess CYA is added with every tab.

It is not excess IF you need the CYA. I would, instead, say:

1. CYA is added with every tab

You are starting to get it!

Kim

 

[Kiss4aFrog]

I'm splitting hairs but I have to toss this out there. It's not necessarily "Excess" CYA as you'll lose some from splash out, backwashing a filter, vacuuming to waste, ... just depends on your equipment and pool use how much CYA is leaving the pool.
Anything that removes water from the pool will lower your CYA. So chlorine tablets aren't all bad just need to be used in moderation.
Sooooooo adding a little CYA is normal for any pool it's just a matter of how much and not adding too much. We think in your case you've finally reached that tipping point where the CYA is so high it's starting to prevent the chlorine from doing it's job.
That's why it would be very helpful to get some readings on the water. When I used to use the pool store they were usually pretty good but there were times I'd have the water tested one day and the next day the CYA reading was off by 40 !! Then there was the time they sold me the more expensive sanitizer that included calcium. But since I have a vinyl pool I don't need calcium. This was all before I found TFP. My point is to be careful of relaying on the pool stores too much since their main goal is making money from you. Expecting them to be the experts isn't necessarily what you're going to get.

Because of your traveling it sounds like going with a SWCG would be the likely way to go. There are plenty of folks here that just emptied the nature unit or in line chlorine tablet holders and switched over to liquid bleach or a SWCG.
On the tablets, hopefully you're using a floater. Over time they can really do some damage to your skimmer/plumbing sitting in there when the pumps off.

 

[Knucklehead]

Squirk, I know this has to be frustrating information as you've already made an investment in the Nature 2. But this process works. I took over a pool about 5 years ago and by the end of the first year I was fighting algae. The pool store kept providing me additives and the data I was working with was inaccurate. I found this website and purchased the TF-100 test kit. I followed the process here. I did my SLAM, got rid of the algae. Now the only things I add to my pool are Chlorine, Acid and CYA. The water I have here is very low in acid. I add CYA and monitor. If I start to get low, I start using the powder chlorine. I stop when I'm where I want to be.
In my mind, the two critical items are to get the test kit and to follow the SLAM process. You are only and good as your measurements.

 

[squirk]

I hate to necro, but I just wanted to thank you all for your help. I stopped adding shock, dialed the chlorine in my Nature2 down from "6" to "2", drained off some water, and the algae problem seems to have resolved. CYA is still a little high, but I will just drain off some more water and see how that goes. I will also switch to chlorinating liquid vs. powdered shock going forward.

Much appreciated!

 

[woodyp]

The more you can get under control before summer rolls around again-----the better off you'll be. Alga and heat are a tougher combo than this time of year.