Full Drain, Partial Drain, or Not Drain......

[Daniel Zeh]

From a first time poster, thanks to all those who support this forum and to those who've come before me with similar issues. Words can't express the sense of empowerment I've gained from reading through so many posts and thoughtful advice.

I've already taken some proactive measures, purchased proper test kit and liquid chlorine. Been wrestling with mustard algae on and off for 6 months. In the last week or so though, it's come on strong on the shadowed wall of pool and on steps/corners. After reading a bunch and dropping a gallon of 10% HCL yesterday, it appears to be slowing down and have been brushing daily. Lots of leaves dropping from a fruitless mulberry close by that I'm staying on top of. Have been breaking down my DE Quad filter every 2 months based on advice from my old pool guy (even though the pressure doesn't indicate a problem). Given this is a year old pool I'm having a hard time understanding how my CYA and CH got so high so quickly. My only guess is old pool guy had summer workers who didn't know what they were doing and used wrong kind of shock every week. I assume I need to do a full drain, but seeking input. From what I've read, I'll never get my FC high enough with CYA level where it is to knock out the algae. My old pool guy says that I might as well do the full drain because if I do a partial and refill and it doesn't reduce CYA enough, I'm throwing money out the window.

My local pool supply store rep advised that their pool's CYA dropped over the winter from 150 to 50 without doing anything. They also advised that if I do decide to drain, that I should acid wash the plaster to ensure all the algae is knocked out. None of this makes sense, hence why I'm here. Thanks in advance for thoughts or links to similar threads that I may have missed.

Today's test results below from my Taylor K-2006C kit.
FC 6.0
CC 0.5
pH 7.4
TA 90
CH 625
CYA 150

 

[Jimrahbe]

Daniel,

Welcome to TFP... A great place to learn how you pool really works...

You do have to drain enough water to get your CYA down to about 30 ppm.. And then you will need to do a SLAM... SLAM Process

There is no reason to do an acid wash as all that will do is make your plaster rougher.

I really doubt that you have mustard algae, as it is not all that normal....

Adding more chemicals to your pool is not really going to do you much good until you drain and refill..

Thanks,

Jim R.

 

[duraleigh]

Welcome to the forum

None of this makes sense, hence why I'm here.

Good it doesn't make sense to me, either.

1. Draining 50% of your pool water cuts your CYA by 50%.......it's a direct replacement so you can get your CYA manageable easily

2. Acid wash is not an algae treatment and should not be used as such......chlorine kills algae.

3. CH builds in your pool continually.......what is the CH of your fill water?

4. Your CYA got so high from using pucks........you'll need to get away from those.

In your climate, I would suggest your lower your CYA now with a partial drain/refill and get CYA down to around 40-50, then bhe prepared to SLAM your pool to get your water crystal clear.

 

[DorsalSpine]

How do you winterize a pool in Austin? What is winter weather like? In my neck of the woods my water freezes and I see the CYA levels drop by as much as 30 points over the winter. Keeping it clean with a CYA of 150 is near to impossible long term. You can drain water and/or hope the level drops over the winter if your water gets cold enough to degrade the CYA. I'd guess you are looking at a water exchange in your future.

 

[ajw22]

Consider doing a No Drain Water Exchange to get your CYA down to 30. That is about an 80% water replacement, around 12K-14K gallons.

Then do the SLAM Process to clear the algae out of the water. Follow the SLAM Process step by step with no shortcuts and it should go fairly quaikcly, hopefully a few days.

 

[Daniel Zeh]

Daniel,

Welcome to TFP... A great place to learn how you pool really works...

You do have to drain enough water to get your CYA down to about 30 ppm.. And then you will need to do a SLAM... SLAM Process

There is no reason to do an acid wash as all that will do is make your plaster rougher.

I really doubt that you have mustard algae, as it is not all that normal....

Adding more chemicals to your pool is not really going to do you much good until you drain and refill..

Thanks,

Jim R.

Thanks! I thought it must be mustard because of it's yellow appearance. Full drain it is!

 

[Daniel Zeh]

How do you winterize a pool in Austin? What is winter weather like? In my neck of the woods my water freezes and I see the CYA levels drop by as much as 30 points over the winter. Keeping it clean with a CYA of 150 is near to impossible long term. You can drain water and/or hope the level drops over the winter if your water gets cold enough to degrade the CYA. I'd guess you are looking at a water exchange in your future.

According to my builder, there is no option to winterize a gunite pool in Austin. We get the occasional below freezing day or week but no deep freeze like our northern friends. Was hesitant to go ahead with the full drain until I got some real validation that I wasn't crazy. Wife thinks I should call a professional and I said "you're looking at him!" Tested CH at the tap and got 40ppm so well below my current level of 625. Appreciate all the responses.

 

[JJ_Tex]

Wait, why a full drain? You will have to add back CYA if you do that. Read up on the water exchange process above as that would be better in my opinion.

 

[ajw22]

According to my builder, there is no option to winterize a gunite pool in Austin.

Sure you have an options to winterize a gunite pool in Austin. You may not want to but you can if you would rather not deal with the pool for a few months. Nothing about a gunite pool in Austin precludes from lowering the water level, blowing out and plugging the lines, draining the equipment, and covering the pool.

Keep your eye on that your "builder" tells you.

Closing an In Ground Pool

Winterizing a pool is essential for keeping your in-ground pool protected during cold-weather months. This Pool Repair guide will show you how to do it.

www.troublefreepool.com

 

[Daniel Zeh]

Wait, why a full drain? You will have to add back CYA if you do that. Read up on the water exchange process above as that would be better in my opinion.

I read the article and it felt like a slightly more complex process than draining and refilling and worried that if done incorrectly, I'd put a lot of water in and not get the levels down low enough. But based on your comments and previous posts that indicate 50% drain should yield 50% reduction in CYA levels, I opted for a 75% drain since my CYA was 150 and CH was 625. 75% reduction would put me right where I need to be methinks. I'm refilling now and will post my levels once full to confirm my hypothesis.

 

[Jimrahbe]

Daniel,

I'll be interested in how this turns out for you.. I am not much of a fan of trying to guess how much water to drain.. You could be right or you could be way off...

Much easier to drain almost all of it....

But that is just me, and to be honest, I have never had algae and have never had to drain my pool, because I have always used the TFP process...

Thanks,

Jim R.

 

[Daniel Zeh]

Daniel,

I'll be interested in how this turns out for you.. I am not much of a fan of trying to guess how much water to drain.. You could be right or you could be way off...

Much easier to drain almost all of it....

Happy to report the results were in line with my expectations of dropping the water by 75%, and achieving a 75% reduction in CYA and CH. This puts me right in the ideal range I believe. Test results now that pool is refilled:

FC 0.4
CC 1.2
pH 8.2
TA 70
CH 210!
CYA 45!

I've put some acid in to bring down the pH. As soon as I'm level, it's onto the SLAM! Any wisdom to share on the SLAM based on current state?

 

[ajw22]

Your CYA is 50 for the purposes of the FC/CYA Levels. So your SLAM FC will be 20.

If the dot disappears between 50 and 40 we round up and call it 50. You can;t judge halfway between lines as 45 since the scale is logarithmic, not linear.