Stubborn Yellow Algae

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LVChris

LVChris

Well-known member
Jun 4, 2015
52
Las Vegas, NV
Pool Size
25000
Surface
Plaster
Hello, I'm new to this site and am happy to have found it. We purchased our house 2 years ago with an existing pool and have had trouble from day 1. We are previous pool owners (10 years) and never had problems so this has been frustrating :mad:.

We had the same algae problem last summer so after following the recommendations of our local pool store several times with no luck we decided to have the pool drained and acid-washed. Once that was completed I purchased the Taylor K-2006 kit to make sure all chemicals were kept in check. I've noticed the pH goes up quickly on this pool and I'm constantly adding acid to keep it closer to 7.5-7.6. I brush constantly but have been getting the yellow spots in the deep end on the wall and steps. I tried raising the FC to keep it near 5 in order to try and control the yellow algae but every day I go out and see new spots. I use a floater for the chlorine tabs and keep it wide open and I've also added dichlor to raise the FC. I added 8 oz of Yellow Out several days ago and then raised the chlorine again. After reading a bunch of posts I'm guessing you're all cringing with the mention of the yellow out and tabs! The water is pretty clear and I wouldn't describe it as cloudy. There is very little debris that gets into the pool and I cleaned the filters on May 5th.

The pool is approximately 20K gallons, in-ground plaster, with a new Pentair Intelliflo VS 3hp pump running 8 hours (4 hrs @ 2800 rpm and 4 hrs @ 1500 rpm). There is a waterfall feature, Hayward sweeper and Hayward SwimClear Cartridge Filter.

Thank you!

20K gallon in-ground plaster, Pentair Intelliflo VS 3hp pump, Hayward Sweeper and Swimclear Cartridge Filter, waterfall feature
 
Welcome LVChris. :wave: I'm a Vegas native myself (Rancho Class of '81). :) TFP can help you for sure. Great have a good test kit and know how to use it. Here's a few quick pointers before others chime-in:
- Stay out of the pool store for advice or products; waste of time
- Algae simply means you need to use the TFP "SLAM" procedure (linked below) which focuses on maintaining the appropriate level of FC based on your CYA level
- Do not use any more "bags of shock" or tablets as the pool store may advise; you will use regular liquid bleach when using the SLAM method.

The links below in my sig speak more clearly of all of this and will help get you on track. More to follow. Welcome!
 
Thank you Texas Splash - Chaparral Class of '78!

I've seen a lot about the TFP SLAM but haven't seen anything about how much bleach I should have on hand before I start this process. Living in LV it seems risky to remove the chlorine float (old habits die hard) but once I get started on this I'm sure everything will be fine.

I forgot to mention that today's tests showed: ph=7.6, TA=100, FC=4.5. I haven't checked the CYA in months because I only had enough for one more test and haven't re-ordered and wanted to make sure I gathered as much information as possible before doing the test. I will do a little more reading - thanks again!
 
Small world huh? :) Not to worry about the water and TFP - it will work. Just need to stay committed and be a little patient, and as you stated ... break some old habits. Pool store habits are the toughest to break, but you're armed with a good test kit, so you should be fine. Many of us have done a SLAM before, and you can too. The bleach works great and has next to no residual effects on your pool or other chemicals. Make sure you reference my links below to ensure you are using the right amount of liquid bleach required to maintain the proper FC level for your pool based on the current CYA (see Chlorine/CYA chart). You need to know your current CYA for sure. Once you know your current CYA, you can use the Poomath Calculator link below to enter your "NOW" and "TARGET" figures for FC and CYA. The calculator will tell you how much bleach to put in, as well as stabilizer if your CYA was too low. If your CYA is really too high because you've been using pucks and pool store bags of shock for a long time, let us know and we'll re-address and go from there. The links below help to show you want those numbers should be. If you get stuck, let us know.
 
I'm not sure if I'm replying correctly so please feel free to comment ;).

Just checked the CYA level and it is above 100!

What is FAS-DPD reagent? - Nevermind - found it-powder to test Cl level.

Thanks!

- - - Updated - - -

It looks like I need to do a partial drain and refill. I'm guessing this will need to be done every year since we completely drained the pool last May.
 
Partial drain is what we see commonly referred to as a "TFP learning experience". :) Just about all of us got "stuck" by the pool store, their advice, and their products which resulted in extremely high CYA and the use of wasteful products and the loss of $$$. Once you get that CYA number down and rely solely on liquid bleach, you won't have to worry about CYA getting high. Good thing you have your own test kit with refills on the way.
 

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Thank you. Just so I'm understanding correctly, are you saying to hold off on the partial drain and refill until I've used the liquid chlorine? I've read all of the links posted by you and jblizzle :eek:. I'm assuming the CYA level is so high because I added Dichlor yesterday or the day before?
 
The CYA is high because of the Dichlor and ALL the Trichlor tablets you have used in the past.

You need to lower the CYA level ... and THEN stick with liquid chlorine in the future.
 
once you have the refills for CYA, you will need to test 50% tap water and 50% pool water and times it by 2 to see just how high your CYA is.. It is not an exact test but its close + or - 20
 
You got it Chris. As you can see, lots of great advice. Post some new results after the refill of the pool (and arrival of your test kit refills) and we'll be glad to help you further. The test kit refills "should" get to you fairly quickly. While waiting on the refills (after your pool is full again) it won't hurt to add some regular liquid bleach to your water to maintain a healthy FC level and to keep things at bay to help avoid an all-out major algae bloom. You won't be able to SLAM until you read that new CYA, but the fresh liquid bleach will help you sanitize the pool somewhat while you wait. Hope that all makes sense.
 
Texas Splash said:
You got it Chris. As you can see, lots of great advice. Post some new results after the refill of the pool (and arrival of your test kit refills) and we'll be glad to help you further. The test kit refills "should" get to you fairly quickly. While waiting on the refills (after your pool is full again) it won't hurt to add some regular liquid bleach to your water to maintain a healthy FC level and to keep things at bay to help avoid an all-out major algae bloom. You won't be able to SLAM until you read that new CYA, but the fresh liquid bleach will help you sanitize the pool somewhat while you wait. Hope that all makes sense.
Click to expand...

Thanks for all of the great help. One more question, does it work well to place the pump in the deep end of the pool and a hose in the shallow end to get the exchange of water or is it best to just pump and then refill? I'm assuming I need to empty about half of the water? The pool is approximately 20K gallons.
 
It is more efficient to drain and then refill, but in some cases (high ground water level, worry about heat/sun on plaster) it is safer to drain and fill at the same time.
 
Well, the limit of the test is 100, so,we really don't know how much above that you are. We generally suggest about 33% drain/refill with reports of 100 CYA.

I didn't see anyone else mention this, so I'll just add - you did an acid wash which exposes "virgin" plaster. You will,have rising pH for about a year, then it,should drop to,whatever normal is for your pool. The first three months are usually the worst for pH rise.
 
Thank you. I thought I read that some where so thanks for the confirmation. The pH has been running high and I've been adding acid like crazy. It was a year in May so I'm not sure if it's gotten much better!

Any suggestions on how much chlorine I should add until I get the results of my next CYA test after the pool is filled back up?
 

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