Water with blue hue

[kal2002]

Hi everyone,

We are located in northern California. Although the weather had been unusually warm for this time of year, the pool water remains cold - around 50 degrees. So instead of adding chlorine to the pool, I just use 2 tablets. The pump runs for 4 hours at night. Last weekend, the water looked a little bluish. I did not not add chlorine to it until this weekend. The test results from yesterday afternoon are:
PH 7.8
FC 11
TA 90
CH 340
CYA 60 ( I think it is low since I tested in cold pool water)
CC 0

I added more chlorine after the test so it was at 16 this morning. Because the water still looks bluish, I added another half a gallon of 12.5% chlorine. The pump now runs for 5 hours instead of 4.

My question is: what is making the water look bluish? Also, it does not look clear.

Thanks.

 

[kal2002]

By the way, I like this upgrade. It is quicker and more impressive.

 

[jblizzle]

Likely it is just cloudy which is giving it a bluish hue.

I am confused though, why do you think a CYA of 60ppm is low? That is actually higher than recommended for a non-SWG pool. And the tablets are raising it more.

Given the cloudiness, you may want to perform the OCLT to see if something has started growing and then follow up with the SLAM process to clear it back up. If you pass the OCLT, it may just be that you are not running the pump enough to keep the water clear of dirt.

 

[linen]

When you say "bluish" do you mean also slightly cloudy? Edit: jbiz beat me

 

[pwrstrk]

When you do your CYA test let the sample come to room temp if your water is cold.

 

[kal2002]

I just did another CYA test with room temperature pool water, it is still 60. When I said CYA of 60 is low, I meant that it used to be higher. I used liquid chlorine in the summer and tablets in the winter when we had rain. This year has been dry so not much rain to dilute the pool water.

When I said the water is bluish, I guess it can be cloudy. It appears bluish and cloudy on the deep ends. Where the steps are, the water is clear.

I wonder if this problem has to do with the pool filter. It probably needs cleaning but we won't be able to get to it for another 2 weeks. When we had a pool service and the pool filter was dirty, I don't remember the water appearing bluish or cloudy.

I thought algae does not grow in water temperature of below 60 but maybe it does when the outside temperature during the day is in the 60's.

 

[pwrstrk]

I would nix the pucks and go with liquid chlorine only. The pucks will raise your CYA level with everyone you use. Your CYA level is slightly out of range for a non SWG pool. Ideally you want your CYA level to be 30 - 50 ppm range.

 

[jblizzle]

Algae can always grow, the rate is slower as the water temp drops. If you let the FC get too low for a long time, it could certainly be trying to take hold.

 

[duraleigh]

Yeah, we all started out thinking 60 was a good cut-off for algae but it's not an absolute.
Tougher for algae to exist but some species can "brave the cold" and slip in and grow slowly.

I think you are on a good path when you clean your filter. You should be monitoring your psi for a 25% increase and clean/backwash anytime you get above that......it makes a difference.

 

[kal2002]

I am hoping it is not algae, just a dirty filter.

 

[jblizzle]

I would not hold my breathe. My pool went for 2 weeks in the summer with no pump ... bottom was a little dirty, but water stayed clear due to adequate chlorine.

 

[pwrstrk]

Like Jason mentioned earlier, try the OCLT test. That will tell the story.

 

[Isaac-1]

Clear blue could be metals in the water, adding more chlorine tends to cause them to get worse because it pushes more past the saturation point. Most commonly we see this with brown or green (iron or copper), but it could be something more exotic, hopefully Chemgeek will chime in.

Ike

p.s. I think I even recall an incident someone had in the last year or two with purple water

 

[JamesW]

I'm thinking copper. Do you have a heater? Are you putting the tabs in the skimmer? Any other source of copper, such as from algaecide?

What color is the plaster? Has the pool ever been painted?

When you pull the cartridge, look for blue staining.

 

[kal2002]

No heater and I put the tabs in the floaters. I don't use algaecide. The pool had not been painted that we mm know of. The color of the pebbletec is the natural pebble color. Nothing fancy.

The tiles above the plaster are blue. Maybe they are reflecting in the water?

- - - Updated - - -

I did several OCLT tests this morning. The numbers were strange.

 

[Patrick_B]

No heater and I put the tabs in the floaters. I don't use algaecide. The pool had not been painted that we mm know of. The color of the pebbletec is the natural pebble color. Nothing fancy.

The tiles above the plaster are blue. Maybe they are reflecting in the water?

- - - Updated - - -

I did several OCLT tests this morning. The numbers were strange.

Can you be a little more specific and post the numbers?

 

[kal2002]

Sorry, tablet issue. In the middle of my reply, it rebooted

 

[kal2002]

I did 3 FC tests yesterday evening. The results were: 34, 44, 39. This morning the results were: 48, 41. The strange thing was, when I was mixing the water with the chemicals, the first batch was light pink. It did not look right so I threw it out. The next batch was bright red so I got 48. Just to confirm, I did a third batch and it was super light pink. I dumped it and did the 4th batch and I got 41. I am not sure what this all means.

 

[jblizzle]

Sounds like you were not using enough powder ... with FC that high, you likely need 2 scoops. You should always start off with a nice deep pink.

 

[Patrick_B]

Strange...

Could you be sampling near a puck? Could you be taking samples at differing depths? Could you be waiting too long to test? Are you putting about the same amount of powder in, and using the same sample size each time?

Sorry for the questions, but all these come to mind with the numbers you got here.