Hello, I need help!

[andrew9]

Hello
I am a pool owner in trouble... as you can guess....


I have a 11,000 GAL in ground plaster pool, tap water.
1/2 HP and Hayward 210T sand filter. Same filter and same pump used to keep it crystal clear last autumn.

Known water params:

FC =4
PH = 7.6
TA = 90
CYA = ???
TDS = 670
Calcium = ??? (This was OK few months ago.

The issue is that I cannot clear the water, being cloudy/ greenish for the last two weeks
Filter is running 10-12 hours a day.

I shocked it, and it cleaned a lot, but still far from where I know it used to be.

Pool plaster is in poor condition, and needs to be replaced, but I try to get by one more year.

One aspect is that the filter now runs without DE, and the pressure sometimes goes down.... instead of up....
Say one evening runs at 12PSI and in the morning it runs at 10 PSI..... without any changes I am aware of.

A week ago I did open the filter to check the sand and it did not look channelled to me. It needed some sand so I added till sand is about 10 inches from the top. I know the manual says 6 inches.... can this be the main issue?

In the past it used to filter better with 1/3 cup of DE added, now I have to add about one full cup of DE....

Does anyone have any advice?
Thanks in advance

 

[duraleigh]

being cloudy/ greenish

A filter, regardless of how good, cannot clear a pool that has algae and you have algae if you see green.

Certainly, you need to have the correct amount of sand in the filter but that will not fix a green pool. The presence or absence of DE in a sand filter isn't related to live algae, either.

read "The ABC's of Pool Water Chemistry" up in Pool School, then read "How to Shock Your Pool".

If you will follow the shocking instructions to the letter, your pool will clear and you can recharge your sand filter to the correct level and have a troublefree season.

Now, here's the caveat, you cannot perform the shock process in your pool until you know your CYA level. Your own accurate test kit will help you test your water properly and save you a lot of time and money.

 

[Isaac-1]

Welcome, first off everything Dave said, I suspect you have just attempted blindly shocked your pool the way most pool stores teach, Dump in X amount of a Chlorine product that they sell as "shock" this could be any type of chlorine product, if that does not work come back and buy more, try 2X, repeat, then try it with algaecide, each time giving the algae enough time to grow back between doses. This is great for the pool stores profit margin, but not so great for the pool owner or the pool. What we teach is understanding of what is going on in your pool and detailed testing, therefore we teach sustained shocking at a level that will not damage pool equipment or bleach out liners, but will kill algae, and we teach keeping it up until all the algae are dead. This does sound like it takes more work than the dump and forget method that pool stores teach, but the truth is if you follow our methods you will rarely need to shock your pool, only in disaster situations like after a major storm causes run off to get in the pool, or equipment failure that causes there to be no circulation for a number of days,etc.

There are 2 keys to making our method work though, 1 is knowledge of what chemicals do, and how to use them, you can learn this in the pool school link in the upper right of this page (most people get more out of it the 2nd or 3rd time through). The other key part is knowing what is going on in your pool, this means having a high quality drop based testing kit, I personally use the TF-100 (see my signature), but the Taylor K-2006 will work also, as we have found pool store testing on average is not reliable, also when clearing algae like you have you must test frequently, often hourly for the first few hours, while boosting the chlorine level to the desired point as it is used up by killing algae.

Ike.

 

[harleysilo]

Hi Welcome!

Your post contains some info that strikes me as "lukerish". How are you obtaining your test results? Why no CYA number (i'll admit that test can be a pain). Shocking your pool is a process, not a one time kill/nuke of the algae. You still have algae growing in your pool water/plaster/nooks/cranies. You need to keep your FC level at shock value until your pool water looks perfect. You can read all about this in the links duraleigh provided above.

It wouldn't hurt, when you go to add more sand to your filter, to give it a good cleaning (eliminating any channeling you may not see) per the article in pool school my-sand-is-channeled-how-to-fix-it-t7626.html

 

[andrew9]

Thanks for your help folks!

My drop kit ran out of CYA reagent and the previous time I had my PS checking the water they either did not measure CYA or they miss-measured it.

I had it measured twice today and CYA is 150ppm or more ; I believe this screams - drain the pool now !!!

What I do not understand is how during one year, the CYA went from basically 0 to 150++.... while running through 1/2 bucket of chlorine tabs during one year,
Does this sound normal to you?

Does store brand liquid bleach contain any CYA?
Or maybe the phosphate remover I used this spring??

I'll drain it tomorrow, brush the walls and then fill it up again

Thanks for your help.

 

[BoDarville]

Hi andrew9:

What I do not understand is how during one year, the CYA went from basically 0 to 150++.... while running through 1/2 bucket of chlorine tabs during one year, Does this sound normal to you?

I'm not sure where you are located and how long your pool swim season is, but yes, this can happen. Using my pool as an example, If I used only two 8-oz trichlor tabs a week (52 weeks) for chlorine and nothing else, I would be at 150 ppm CYA.

Now, let's assume the pool is operational for 1/3 of the year and winterized for the remainder of the year. Using my pool's volume, if I used two 8-oz trichlor pucks a week for 17 weeks, that would give me ~49 ppm CYA. Since most people who use trichlor very likely also use dichlor once a week to "shock", let's also add 2 pounds of dichlor per week for 17 weeks. This adds another ~89 ppm CYA. The total CYA added would be ~138 ppm. So, yes, 150 ppm is very doable.

Does store brand liquid bleach contain any CYA?

Nope.

Or maybe the phosphate remover I used this spring??

No CYA there either. However, phosphate removers are unnecessary in a properly chlorinated pool.