Green just won’t go away

[rnaval]

I’m struggling with a pool where the green just won’t go away, here’s picture of the extent of the green. It was taken after I brushed floor and walls.

https://drive.google.com/open?id=16rTBsstf4j5JH3g-omUic_Nxd9dAA5-4

It’s a summer place so I can only be here once a week to look after it.

It’s a 33k inground vinyl pool with a sand filter. I find that I need to keep the FC level high around 20 or more just to maintain a somewhat clear pool but it always shows some green when I return after a week as you see in the picture.

FC=20
PH=7.5
Alk=70
CYA=30

I’m going to try adding DE today to the filter, will it help in my case? 1-2 cups.

Any suggestions?

 

[mknauss]

How are you chlorinating on a daily basis if you are only there once per week?

Please add a signature. Read Pool School - Read This BEFORE You Post
Information in your signature will show up each time you post and it makes advice more accurate as we know what equipment we are dealing with.

 

[rnaval]

I’m not, only weekly with slow chlorine tabs in the chlorinater and a bag of shock once a week.

 

[mknauss]

You have a CYA of 30 using tablets and shock (I assume it is cal hypo).

You will not clear the pool that way.

You cannot SLAM Process once per week. And that is what you need.

 

[rnaval]

What do you suggest?

 

[mknauss]

A signature that I requested above would help to know what we are dealing with. The picture will not work for me as I do not get on Google Drive.

If you cannot be there or have someone come by over a several day to week span, not much you can do. You can keep it like a large number of pools are kept, cloudy and frequent algae outbreaks. But TFP, no way.

If you add a SWCG in the future you would have a chance.

 

[rnaval]

Added the signature. I listed the numbers incorrectly earlier.

Here are the correct numbers. I can see I need to up the FC to at least 39, correct? To lower the CYA, I’ll empty and refill the pool partially.

FC=26
PH=7.8
ALk=70
CYA=over a 100

I do plan to install a SWCG this month.

 

[mknauss]

Your real CYA is likely far above 100. Use Step 8 in Pool School - CYA

You will need to drain and solve the algae issue prior to SWCG.

 

[rnaval]

How much pool water should I drain / refill? Could the CYA level be temporarily showing high because I added 2 bags of shock?

 

[mknauss]

What is 'shock'? That describes many different pool store items. But no, it would not be temporarily high. It is high because of a steady diet of trichlor and/or dichlor.

You will most likely need several drain/refills depending on how high your CYA. An indoor pool only needs 20 ppm or so of CYA.

 

[rnaval]

By ‘shock’ I mean Dichlor and the slow tabs I use are Trichlor. I managed to empty the pool partially and refilled to get cya down to 60. I’ll now use liquid shock only and bleach so they don’t introduce any cya into the pool. Does the cya ever go away on it’s own? Even if I wait until next season?

 

[mknauss]

CYA primarily goes away by draining water from the pool with it (due to overflow, winterizing, etc) and replacing with fresh water.

There is a very small degradation of CYA due to high water temperatures (not likely for you) and elevated chlorine levels.

Certain circumstances do occur, normally in winterized pools, where a bacteria attacks the CYA and creates ammonia in the water. That is not a good thing, as it takes a very large amount of chlorine to eliminate the ammonia.

 

[rnaval]

Pool looks really good now. Final question, should I install the swg now given that the pool will be closed in a few weeks or wait until next season?

 

[mknauss]

I would suggest waiting until spring to install the SWCG. You should be able to maintain your FC with liquid chlorine pretty easily until your water gets to 60F when you close.

 

[rnaval]

I’ve installed the SWCG, I will not turn it on until next season. Is there a recommended type of salt to use, thinking of stocking up on it now. It’s sold at Homedepot, Lowe’s and Walmart but there are different varieties.

 

[mknauss]

Plain water softener salt. Typically the blue bags.

 

[rnaval]

Getting ready to open the pool in a few weeks and startup the newly installed SWCG, do I wait until the pool is clear and then add the pool salt and startup the SWCG? Does it matter in which sequence I do this?

 

[mknauss]

It is best to test your pool chemistry and determine if you need to SLAM Process. If so, complete that and then add the salt and get your CYA in range, etc.

 

[rnaval]

Thanks, sorry for the second posting, you can kill it. I wasn’t sure if I should have revived this old thread or post new.