Bottom of pool is green

[Kristine D.]

Hello. I'm new to this forum. I am learning about pool care, slowly. Our family had our new 7600 above ground vinyl pool installed last summer and have had great luck with it so far. Yesterday we peeked under the cover and discovered the entire bottom is green. Oh no! It's only on the bottom and it wasnt like this a week ago! Nothing on the sides. The water is still very clear. I brushed a strip to see what would happen, it stirred up a cloud but the liner looks clean underneath.

The filter pump and the salt chlorine generator have been running every day for three hours for the winter months.

The pool has had a plastic cover on top of the water, but not over the sides to help keep out debris.

I took a water sample to the pool store to have it tested to make sure I got accurate results.

We have had recent unusual hot weather (80 plus degrees) this past week.

This is our equipment: 7600 gallons, vinyl liner, metal sided pool. Hayward EC40C90 DE filter/ 1.0 HP pump combo and a Hayward Aqualtrol T cell 5 salt generator.

Here are today's water test results:

Free chlorine: 5
Total chlorine: 5
Salt: 2500
Cyanuric Acid: 39
ph: 7.6

We didn't think our levels were too bad. The salt cell is clean. The pump is working fine, the DE filter pressure is fine. We "bumped" the system today.

I located some posts here at TFP about green substances that were not algae. So I decided to get some expert advice before throwing chemicals in.

We have a huge Eucalyptus tree right over our pool that constantly drops leaves and seeds into the pool so we are always removing debris. We have a large amount of grass around the pool that gets mowed every week. For these reasons we have kept the cover on, but the cover just sits on top of the water, it's not pulled over the sides and tied like it should be.

We added some salt and put the salt generator on the boost setting.

I'm keeping my fingers crossed that it's not algae. Can someone please instruct me on the chlorine loss test to figure out if its algae? If it is, what is something safe for the pool and for us to get rid of it?

Thanks for reading and for your advice! Please excuse any typos.

Kristine D.

 

[jblizzle]

Welcome to TFP!!!

I would have to first suggest that you get one of the recommended test kits that includes the FAS-DPD chlorine test. That is the ONLY test that will measure the high FC levels required to clear a pool following the Shock Process as described in Pool School. Also, testing yourself will give you MUCH more accurate results than taking it to any pool store.

Please read through the articles in Pool School if you have not already as they will give you a better understanding of your pool and its chemistry and within hours you will know more than most pool store employees.

If you have had a cover on the pool, I am not really sure how it would not be algae. Although is it suspect that it is only on the bottom.

You will need the FAS-DPD test in order to perform that OCLT (pool-school/overnight_fc_test) correctly.

If you prove that it is algae (you could just scoop some out and see if it is slimy), then you need to follow the Shock Process using liquid chlorine.

BTW, your salt result does seem low, but the fact that your FC may have been over 5 ppm (the max the pool store can likely test too), probably means the SWG was still working.

 

[Kristine D.]

Thank you Jason!

Follow up question: since I have a vinyl liner, is it adviseable to use liquid chlorine to shock? At the time of set up I was told only powder and that I must dissolve the powder in water before adding to the pool.

Assuming before testing that it's algae, is a separate algicide required in addition to chlorine shock?

 

[duraleigh]

Hi, Kristine,

Welcome to the forum. :lol: You will not need a separate algaecide. What city and state do you live in?

It is unusual for a covered pool to have algae this time of year although that's very likely what it is.

 

[Kristine D.]

Thank you! I was hoping you would say that. I am in Southern California.

 

[duraleigh]

So Cal. So your pool is not "closed" for Winter but simply has a cover. It almost surely is algae but your test results wouldn't indicate that. Has the FC been allowed to be lower? How often are you uncovering the pool?

Do you have a pic you could post?

 

[Richard320]

As soon as I read 80 degree weather, I suspected you were local...

If you got that FC 5 from color matching - it's wrong. Anything from roughly 4 to 7 looks like 5 to me. You will need a FAS-DPD test kit to measure accurately. It's all in pool school. In the meantime,

[center:3te3rwxi][youtube:3te3rwxi]uijLXS-IJZM[/youtube:3te3rwxi][/center:3te3rwxi]
Remember: The Shock Process is not a one-time overdose of chlorine. Just like you wouldn't down a whole bottle of antibiotics in one go, but rather bring the level up quick and keep it there for several days.

 

[Kristine D.]

Awesome clip Richard! I took the water to the pool store to have it tested and that's what the print out says. In addition to a photo shoot of the pool, I will be acquiring a test kit tomorrow.

Thanks!

 

[jblizzle]

You will be hard pressed to find one of the recommended test kits locally. Most pool stores do not carry the FAS-DPD test.

The TF100 can be ordered from a distributor in CA. Check the link in my signature.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[Kristine D.]

Well, what a difference a day makes! When I left off yesterday, all that we had done to the pool is add salt, swept lightly, switched the salt chlorine generator to boost/shock setting, "bumped" the DE filter and then let the salt system and the pump run all night.

I was very surprised to see a very blue pool first thing this morning! Here are two photos from around 7:30 am, approximately 14 hours after starting the boost cycle on the salt chlorinator. One photo is looking across the pool. The second photo shows what is left of the green that was originally covering the entire bottom with some stubborn eucalyptus leaves. Would love to read what everyone thinks it was, I assume everyone will say it was algae. It sure disappeared quickly. I know the water is not sparkly like it used to be, but I am pleased that its not green.

I also found many tiny bright green gnats and a bunch of very small green seeds in the filter basket. I tried to get a good photo but they are too small and do not show in the photo.

Here are today's test results from a combo of the pool store and 6 way test strips (I used multiple strips to see if I got the same results, they all came out the same). Today's testing method is temporary to get me by until my mail order kit arrives.

Free chlorine: 10
Salt: 2900 to 3000
Cyanuric Acid: 30
ph: 7.8

Now, the questions:
How long do I need my filter and pump to run continuously?

Should I be worried about the pH reading?

How long do I need to keep the chlorine at this level to be in the clear?

A pool employee told me two things today that I would like to verify or correct:
a) My Aquatrol stops producing chlorine if the water is below 60 degrees true/false?
b) Pool filter pumps need to run for an hour for every ten degrees in outside air temperature true/false?
example: 80 degrees outside, run the pump for 8 hours


Thank you to everyone who replied and helped me! I learned a ton!

Kristine

 

[jblizzle]

Now, the questions:
How long do I need my filter and pump to run continuously?
Until you confirm whether or not it is algae by performing the OCLT and complete the Shock Process if required

Should I be worried about the pH reading?
The liquid pH test will read artifically high when the FC is above 10ppm ... so not likely anything to worry about

How long do I need to keep the chlorine at this level to be in the clear?
There is no way to know what your true FC and CC levels are without the FAS-DPD chlorine test. You should maintain the required shock FC level based on your CYA level (see the table in Pool School), until you pass the 3 tests to stop the Shock Process

A pool employee told me two things today that I would like to verify or correct:
a) My Aquatrol stops producing chlorine if the water is below 60 degrees true/false?
Not sure some SWG stop between 50 and 60 degrees

b) Pool filter pumps need to run for an hour for every ten degrees in outside air temperature true/false?
example: 80 degrees outside, run the pump for 8 hours
False. The pump needs to run long enough to filter the pool clear enough for your personal liking. Although the SWG output is tied to the pump run time and its output setting. So you have to balance pump run time and SWG % output.


Thank you to everyone who replied and helped me! I learned a ton!

Kristine

I still suggest you get one of the recommended test kits if you want to really understand what is going on in your pool. Without it, you can not accurately do the OCLT to test for organics or perform the Shock Process to rid the pool of undesirables.

Usually we also suggest not using the SWG for the shock process and in fact turn it off and use liquid chlorine so that you know how much FC is consumed over a given time period.

 

[Kristine D.]

Thank you for the fast reply and the info. I will continue to monitor and post.