Blue Crystals/Black Staining in Pool

[FLman]

Hello Everyone

New to this forum and fairly new to pool ownership. I have a pool issue which I need some advice on.

We have a salt water pool built in 2017 with Pentair equipment and I have weekly pool maintenance.

My regular pool tech was out sick and someone else came by. After they did, we noticed a lot of blue crystals in the bottom of the spa (see picture) and in the pool itself. Spa water was kind of cloudy. We had never seen this before.

We cleaned some of it out with our pool vac and asked our regular pool tech to clean the rest when he returned the following week (there was a lot in the pool and it did not dissolve for quite some days). Whatever the crystal was there was enough of it at the bottom of the pool that the following week he scooped it out and threw it on the ground by the spa.

Shortly thereafter we started noticing black staining at the bottom of the pool, especially in the areas where the blue crystals had gathered (see pictures). Our pool tech says he has scrubbed the bottom of the pool but it is not coming up (so probably not algae). My tech also replaced the pool filter (which was only 3 months old) and it was also stained blue.

I am no pool expert...a google search leads me to believe that the blue crystal was copper sulfate and the black staining is a result of the excess copper sulfate in the pool. But I am certainly open to other suggestions as to the cause.

I have told this to the owner of the pool maintenance company and he says that they don't use copper sulfate. He thinks the staining could be from copper piping the heat pump reacting with the salt water. He doesn't explain why the crystals and then the staining all appeared within a week or so. He is offering to clean the pool (acid wash) and says that installing a bypass filter so the water doesn't run though the heat pump in the summer when we don't heat the pool may help.

I don't really believe in coincidences so the fact that we saw all of these blue crystals in the pool shortly after a replacement pool tech came by make me think he added something to the water that caused this. But I don't know enough about pool chemistry and equipment to rule out some interaction with copper in the heat pump that suddenly (in the span of a few days) caused staining and left a lot of bluish crystals in my pool.

Any suggestions (and let me know if you need more info)

Thanks!

 

[YippeeSkippy]

WOW. just wow. I'm so sorry you had this happen. In *my* opinion he also put something in the pool with copper in it. Perhaps cheap algaecide.... but maybe also something else that also caused the crystals? Perhaps he lowered your pH enormously which has been known to cause crystals in certain circumstances?
Did he leave behind any notice of what was done & added?

The sad reality is that we hear of poor performance and pool care by others taking care of our pools. Hence we always suggest to those that need to use them that they should own a good test kit and follow behind and test thru the week to monitor the condition of the water. And instruct them to *not* use certain products or to check with the owner before adding anything.

Please take a water sample to a pool store (not related to the business your tech is related to) and ask them to perform a test for copper and metals. Just those. We don't trust their results with the other chemistry, but the metals is worth doing.

Be aware that an acid wash removes a thin layer of plaster and shortens the lifespan of your finish. Easy for them to do, but you get to live with the damage and hope it helped the stains?

I'd ask that you obtain one of the two test kits we endorse and give us a full set of results:
FC
CC
pH
TA
CH
CYA
Salt

Either the K-2006C from Amazon, or my preferred TF-Pro Salt kit from www.tftestkits.net

Maddie

 

[JamesW]

Looks like copper to me.

 

[FLman]

Update:

I've had four different pool companies look at the pool and make recommendations. (Note - I am currently back up north so I was not able to take a sample of the pool water and I am dealing with all of this remotely) They all seem to think that the copper staining is a result of the saltwater interaction with the copper in my heat exchanger (vs something someone put in the pool). No one can really explain all the crystals we saw in the pool...one specialist said that the could have been generated naturally by the salt water interacting with the copper piping.

The recommendations fall into 2 groups which are sort of at odds with one another and I need help figuring out the best course of action:

Group 1) Acid wash the pool to remove (as best as possible) the staining and install a bypass filter so the saltwater is not running through the heat exchanger when the heater is not being used (probably mid-May to end September). This should reduce but maybe not eliminate the issue in the future

Group 2) Acid wash the pool and replace the heat exchanger with a better model using titanium instead of copper piping. This should eliminate the issue in the future (but of course costs a lot more money)

So my questions are as follows:

1) is copper staining inevitable with a copper heat exchanger (my pool has been running for about 4.5 years) or could better monitoring and adjusting of the pool chemistry avoided (or postponed) this problem? ie. does every salt water pool owner with a copper heat exchanger end up with copper stains eventually, or is there something that my pool specialist could have done/not done/done better that would have avoided this problem?

2) I've seen recommendations for acid washing the pool with and without draining it. Is one method preferred over the other? As YippeeSkippy indicated, it seems like acid washing can be hard on the pool's surface. Do I have an alternative?

3) Several specialists have stated that once copper staining occurs it means that the heat exchanger is essentially no good any more and I have to replace it to avoid future staining. Is that the case...or would I be ok with acid wash, bypass filter and better pool chemistry monitoring (at least for a few more years).

4) If I do decide to replace the heat exchanger, is titanium the way to go vs cupro-nickel?

thanks so much for all your help

 

[JamesW]

My regular pool tech was out sick and someone else came by. After they did, we noticed a lot of blue crystals in the bottom of the spa (see picture) and in the pool itself.

99.99999999999999999999999% probability the service person added copper.

What heat pump do you have?

I would try Sulfamic acid followed by a drain and refill if it is safe to do so without floating the pool.

STAIN SOLUTION #2 – The Copper & Scale Stuff | Jacks Magic

jacksmagic.com

 

[JamesW]

The UltraTemp has a titanium heat exchanger.