CYA levels low

[allisonmarie]

Hello & happy pool season!

Last year, I ran into major algae problems because my CYA was way too high from using pool store shock. After draining about half of the pool water for the winter, and replacing it with fresh hose water, I was optimistic that maybe my CYA levels would be just where I want them this year. No such luck - I just tested and the CYA is too low to register on my K-2006 kit. I am wondering if anyone has any advice for how I should go about raising the CYA, as I'm not sure how much is in there currently.

From my research on this site, it sounds like I need to go buy some solid CYA, dissolve it slowly, and retest CYA level in a week or so. The problem is I need to start a SLAM on my pool, and I'm not sure how to go about it without having a concrete number for how much CYA is present.

Which brings me to my next question. I still have several 1 lb packages of pool shock granules - should I add these to get some chlorine & stabilizer in the pool? I know traditional shock is normally not recommended - I'm just wondering if I can get rid of this stuff and maybe start addressing my CYA problem? Right now my FC is zero, so I really need to get some chlorine in there. Would I be better off just putting in some bleach?

So sorry for any silly questions - I started with TFP toward the end of last year and I have a lot to learn! Any help would be greatly appreciated!

 

[Richard320]

Yes, powdered shock can be used to raise CYA. Whether or not it's a good idea depends on test results. Dichlor and trichlor are both very acidic. If your pH is high and the TA is also high, then use it. But if you have to start adding all kinds of baking soda and borax to compensate, it's not much of a convenience.

Have you used Effects of Adding Chemicals at the bottom of poolmath?

 

[allisonmarie]

Have you used Effects of Adding Chemicals at the bottom of poolmath?

I totally missed that section! Thank you - That is very helpful! My pH and TA were both high this evening, so I threw in some trichlor pucks after reading your response. I will see what my levels are like tomorrow. Thanks again!

 

[allisonmarie]

Here are today's levels:

FC - 8.5
CC - 0
pH - 7.6
TA - 80
CH - 220
CYA - High 20's?

The black dot disappeared when the tube was completely full. I added CYA 3 days ago (granules in a sock in the skimmer method) so it still may be too early to get an accurate reading... I probably jumped the gun by testing today, but what can I say? The water chemistry is becoming an obsession.

For the past several days, I have been doing what I would describe as a cautious SLAM, and my water is almost completely clear. I am doing a lot of guess work on what FC level to target during this process, because I haven't been able to get a CYA reading I'm confident in. I don't want to raise FC too high and damage any equipment.

A couple questions:
1. How important is the 'no backwashing for a week' rule? As I said before, I've been SLAMing the pool while waiting for this week to pass, and my PSI is creeping up. I'm not sure how realistic it is for me to wait until Wednesday to backwash. If it's just an issue that I won't get full benefit of the CYA I added, that's really not a problem. I added a conservative amount to begin with (didn't know where I was starting, and I experienced high CYA last year & would rather not get into that position again) and I figured I would be adding in 2 steps to get closer to my ultimate target of 35-40. I guess I just want to make sure that I won't cause any damage by backwashing too early.
2. Is my pool swimmable at the current levels? Chlorine is pretty high, but it's hot and I had to ask

Thanks!

 

[Richard320]

A couple questions:
1. How important is the 'no backwashing for a week' rule? As I said before, I've been SLAMing the pool while waiting for this week to pass, and my PSI is creeping up. I'm not sure how realistic it is for me to wait until Wednesday to backwash. If it's just an issue that I won't get full benefit of the CYA I added, that's really not a problem. I added a conservative amount to begin with (didn't know where I was starting, and I experienced high CYA last year & would rather not get into that position again) and I figured I would be adding in 2 steps to get closer to my ultimate target of 35-40. I guess I just want to make sure that I won't cause any damage by backwashing too early.

If the filter needs it, it needs it. If you put the CYA granules down the skimmer so that they ended up in the filter, you might lose some, but adding more later is easy. You need good flow and filtration, so backwash when needed.

2. Is my pool swimmable at the current levels? Chlorine is pretty high, but it's hot and I had to ask

Thanks!

Yes. With CYA of 20, shock level is 10 and you're well below that, Let the FC drift down and hop in if you want. When you're done, bump FC back up to shock level. While you're in there, it's a good time to take a small brush and scrub around the return eyeballs and inside the skimmer throat and anywhere else it's hard to reach with the pool brush.

 

[allisonmarie]

Thanks Richard! I will make sure to do some scrubbing while I'm in there & I will carry on with the SLAM this evening.

I'm also getting to the point where I want to add DE to the filter for the first time. I can see the bottom of the pool very clearly, but the water isn't sparkling yet. I've read through the pool school article, but I have a question. After I get the correct amount of DE in, and the pressure inevitably raises up from the improved filtering, I know I will need to backwash (this is actually why I've been putting off adding the DE, because I'm trying to give the CYA as long as possible). Does the correct amount of DE need to be re-added immediately after I backwash? From my reading, I am under the impression that the DE will be gone after the filter is backwashed - I just want to confirm. Any advice you think would be helpful for a first timer would be great!

 

[Richard320]

You have it right. The DE forms a filter layer on top of the sand, so when you backwash, it's gone, and you need to replenish it. It doesn't have to be immediately after a backwash-- you have a sand filter so it will keep on filtering the way it has all along. Only add DE when you're around to keep an eye on the pressure and flow, because it can load up in just a couple hours.

 

[allisonmarie]

Got it! Thanks again!

 

[allisonmarie]

I am happy to report that my pool is looking better than ever! I haven't even gone down the DE road yet, the pool just cleared up beautifully while I was waiting for the CYA to be in there a week.

I added my 2nd round of CYA this afternoon and I'm confident this will get me where I need to be. Now I'm letting the filter run for 24 hours. Is it okay to vacuum during this 24 hour period, or would I be better off waiting?

 

[Richard320]

I am happy to report that my pool is looking better than ever! I haven't even gone down the DE road yet, the pool just cleared up beautifully while I was waiting for the CYA to be in there a week.

I added my 2nd round of CYA this afternoon and I'm confident this will get me where I need to be. Now I'm letting the filter run for 24 hours. Is it okay to vacuum during this 24 hour period, or would I be better off waiting?

Vacuum! Get the crud out of the pool so it will sparkle sooner.

 

[allisonmarie]

Vacuum! Get the crud out of the pool so it will sparkle sooner.

My thoughts exactly!