Patio pond is getting Chlorine readings

[Stef]

Hi everyone, I’m having issues with something that shouldn’t be this difficult to control. Chlorine. I have a 100 gal stock tank pond in my patio (Agrimaster black tub). It was set up on April 1. Plants added May 5 (water hyacinth, water lettuce, pond lily). Two comet goldfish added May 20. Chlorine readings have been a problem since the plants went in on May 5. I thought the chlorine was coming from new paver bricks used to elevate the lily pot. On May 16 I removed all the paver bricks and used a ceramic pot upside down instead. I also did a 30% water change. I’ve been using Fritz Complete as my water conditioner and then switched to Prime. Testing every day since the 16th I’ve seen no chlorine readings. I added a sponge filter from another tank assuming I lost whatever BB was on the original sponge filter. I added the two comets on May 20 and everything has been hunky dory. But todays test is showing sky high chlorine. 
 

The fish seem ok. The air temps here in Chicago have been cool. Currently 53 F, pond is heated and is currently at 65 F. Heater set to 80F but can’t keep up. The pond gets afternoon sun. 
 

Other items in the pond are a fake piece of driftwood, 3 fake plants, some seriyu stones, 20 lbs aquarium gravel and several fake lily pads for shade. I have more real plants inside in another tub waiting for warmer weather. But added the fake plants for cover. The soil used for the lily is from Aquascape Inc and its ingredients say 90% loamy sand media and 10% expanded lightweight clay aggregate. 
 

Anything else that you see that can cause chlorine readings?

I dechlorinated again with Prime just before writing this.  
 

From left to right:

Strip 1: showing high Chlorine 

Strip 2: tap water 

Strip 3: Ammonia looks 0 to me

Strip 4: post Prime treatment 

 

[Guppysnail]

I’m so sorry you are having an issue. I remember reading a thread on here last year or the year before that a certain type of pond/tub plastic container was causing high chlorine readings. 
Im sorry I don’t remember the details but maybe use the search and see what you come up with?

[SunBearQ]

Here is one of the threads mentioned.

[Stef]

Got it. Thank you @SunBearQ  I struggle with the search and couldn’t find. I’ve requested an SDS from the company. Though the product description says its “FDA food grade approved poly”. Going to keep on testing for a while, treat with Prime when needed. Thanks again for sharing. 

[Stef]

For what it’s worth, this is the response I got from big box store regarding the SDS request:

“This product does not have a Safety Data Sheet as it does not contain any hazardous components.”

[AnotherHumanPerson]

On 5/26/2023 at 10:15 AM, Stef said:

“This product does not have a Safety Data Sheet as it does not contain any hazardous components.”

Unless you specified that you are looking for hazards for fish, I would understand this response. Most tap water is human safe, but contains enough chlorine to kill fish, hence why we need to dechorinate.

My other thought would be if you have any sprinklers or plant watering systems by the pond that somehow get into the pond, contaminating it with chorinated water.

[Pepere]

Or might you have any sketchy neighbors…

[Stef]

No sprinklers or watering system. And neighbors are all cool and animal lovers too. Newest neighbors are newly fledged Robins. They keep hanging out on and around the pond. Little pooping machines too.