Algae / After Shocking Questions

[0REDSOX7]

Hi all,

Been a lurker here for over a year, with lots of valuable info shared, but I have some questions... first off, I have a “temporary” wal-mart - 4’ deep x 14’ wide - summer waves pool hooked up to an Intex sand filter.

Never once had an issue with algae - but this past week, I was noticing a bloom starting. This, after I realized the pump has not run in two days after a brief power outage in Sunday tripped the power to the house and such, blew the GFCI. .. Doh! Pool temp is sitting at 87 degrees. Here are other relevant pool stats..

pH - 7.5
Alkalinity - 90ppm
Total Chlorine - 4ppm
Free Chlorine - 2ppm

So, tonight I decided to shock the pool. First, I got in and scrubbed the algae off, then vacuumed it and back-washed and rinsed the sand, and then I used Power Powder Plus from Leslie’s Pool as it has done me good over the past two years.

Tonight, about an hour after shocking, I notice what appears to be a brown film like substance (looks like pool filter sand, but isn’t) on the bottom of the pool. Is this from the shock?

Curious, beyond this, given it’s a “seasonal” pool, what else can I do to keep algae at bay? More chemicals?? Drain, clean and refill?

Thank you.

 

[Fast7]

Did you add stabilizer (CYA) to your water? How are you chlorinating? Liquid chlorine or pucks?

 

[Lemonred34]

The brown substance is likely dead algae. Does it poof when you brush/touch it? How are you testing your water?

 

[0REDSOX7]

Yes, it seems to dissipate when disturbed. It’s almost the color of a dead leaf, if that makes sense. Definitely darker than the sand.

I am using an HTH 6-Way test kit.

 

[Lemonred34]

Yes, it seems to dissipate when disturbed. It’s almost the color of a dead leaf, if that makes sense. Definitely darker than the sand.

I am using an HTH 6-Way test kit.

From my quick research that test kit only test total chlorine levels not free chlorine, and even then, unreliable.

We can guide you in the right direction for clearing your pool, but only if we know your water chemistry is accurate. CYA level is very important when it comes to chlorinating your pool and keeping algae at bay.

SLAM Process

FC/CYA Levels

Test Kits Compared

 

[0REDSOX7]

Chlorinating using the pucks that have the CYA / stabilizer already in it - they are in a floating thing that is in the pool and typically has two pucks in it at any given time.

I have the bottle of re-agent from last year to help test free chlorine and is what I have been using. Perhaps this is not the best option?

The new test kit I have does test for CYA - and when I checked it three weeks ago, it was at 30ppm - which seemed to be in range listed in the kit.

 

[Mr Bruce]

Guide for Seasonal/Temporary Pools

Smaller seasonal pools can see just as much enjoyment as their larger counterparts. In this guide we'll show you how to maintain your temporary pool.

www.troublefreepool.com

Your HTH kit is fine for your purposes. I would drain it, clean it and refill it. I'd skip the "shock" in the future and just stick to the guidelines in the article.

 

[Lemonred34]

FC/CYA Levels

You are adding stabilizer to a pool that already had enough. Every time your CYA is increased so is your recommended FC level. Your CYA is over 30 now if that’s what it was 3 weeks ago and you’ve steadily been using pucks. That could explain the algae.

Does the regent for the FC have an expiration date?

 

[0REDSOX7]

Yes, the expiry is next year (2020).

So, with that all said, what are my options? Drain, clean and fill? Switch to liquid chlorine?

 

[Lemonred34]

Personal choice. Is it green/dead algae and all still?

 

[0REDSOX7]

Yes, it was just on the bottom, green spots in the crease of the liner - but like I said, that is all gone and now there are brown patches in middle that looks like dead algae that I vacuum out later tonight. Should I shock again tonight, just in case?

 

[Lemonred34]

Its recommended to do the SLAM Process which does require liquid bleach, it will kill all the algae and bacteria that could still be lurking. It is your pool, your choice, but there’s no way to say that another shock is going to get you where you need to be. It’s likely to come back in a few days or weeks, especially if you don’t follow the FC/CYA Levels. So, if the SLAM process isn’t something you would like to do, a drain/refill would probably be your best option to keep it from returning and prevent any further problems.

Have you done an Overnight Chlorine Loss Test

Are you super opposed to draining/refilling?

 

[0REDSOX7]

No, not at all opposed to draining and refilling - its not a big pool, but, cost is there for water.

Not opposed to the SLAM process, either. Like I said, this only started this past week when I realized the pump had not run for several days (my fault - busy with other things).

I have not done an official overnight Chlorine Loss Test, but, have measured it at night and in the AM, and at times, have not noticed much loss, but, never gave it much thought until this issue arose.

 

[Fast7]

Are you closing your pool at the end of a season or do you drain and take it down completely?
My concern is that, if you have been chlorinating with pucks long enough, your CYA might be too high to allow chlorine to actually sanitize pool.
You really need to know what your CYA is. Then you can make a decision which option would work for you, drain and refill or SLAM.

 

[0REDSOX7]

Yes, pool closes on 9/15 and gets taken down after bleaching and cleaning everything (and drying).

I purchased a Taylor K-2006 kit off Amazon on Monday, given reservations about the HTH kit...

Results as of this morning (Friday, 7/19)

CYA - 40ppm
Total Chlorine -5ppm
Free Chlorine - 4ppm
pH - 7.4
Total Alkalinity - 90ppm

Preparing to do the Overnight Chlorine Loss Test this evening.

After scrubbing and vacuuming and scrubbing and vacuuming the pool is really clear, and appears to be doing okay. No green patches on the liner at the bottom of the pool, so, hoping to stay on top of this without draining and re-filling - as I would rather SLAM than anything else, so, will see.

 

[IceShadow]

CYA of 40 is very reasonable, especially in NC.

 

[Fast7]

Since you had algae I would SLAM it to make sure you killed all of it. For CYA 40 your SLAM FC is 16, so it’s not that bad.

 

[Joe Tiempo]

New pool owner here.. After you shock am I correct to assume you should wait to use pool until the FC level are back to ideal range?

I have high CYA (70 ppm) due to previous owner only using pucks. Need 28ppm FC for shock.. seems like it would take a week or two to get back to my ideal range of 7-8 FC ppm.. Am I missing something?

 

[duraleigh]

Welcome to the forum

I have high CYA (70 ppm) due to previous owner only using pucks. Need 28ppm FC for shock.. seems like it would take a week or two to get back to my ideal range of 7-8 FC ppm.. Am I missing something?

It is safe to swim at SLAM value or less (so 28 ppm is fine). It is also pretty likely that your FC will deplete a little quicker than you think.....lot's of variables but I would imagine it'll be at maintenance level in a few days.