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.

[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. 

[PluckyD]

I wasn't sure if I should revive this thread or start another, but I am experiencing something similar with my outdoor tub ponds. I started 3 tubs this year and have 1 that is over a year old, so 4 in total. I am using the HDX 27 gallon tubs from Home Depot. I never tested for chlorine before, but am now using the Aquarium Coop test strips which include it. After half-filling the ponds and letting them stew for a week, I was quite surprised to find chlorine was still around 2.0.

I thought perhaps my dechlorinator had gone bad (I had transferred some Prime into a repurposed Easy Green bottle), and it no longer smelled stinky fresh, so I ended up opening a new bottle of Fritz Complete. Another week and *over half a bottle of Fritz complete later*, the chlorine still reads high. Perhaps the plastic is leaching something? I did successfully breed a lot of fish in the first tote last year so I hope it's just weird readings, but it would still be nice to know what is going on.

[Stef]

@PluckyD hi. The chlorine issue was frustrating but it resolved itself after about a month of up and down chlorine readings. The chlorine never came back and the fish were fine. Are all 4 of your tubs reading chlorine or just the new ones?

[PluckyD]

On 3/4/2024 at 2:56 PM, Stef said:

Are all 4 of your tubs reading chlorine or just the new ones?

Unfortunately, all 4 are! So I cannot just chalk it up to the new plastic. I kept guppies in the one I had last year but they tend to be so hardy. I’m not sure if they just toughed it out, and maybe another more delicate species might not fare as well. 

[Stef]

Is there any other decoration or plant container that’s leaching?  I had stacked some new paver bricks to prop up my lily pots. After removing them I still had chlorine readings. So I’m pretty sure it was the tub itself. Since I brought my pond fish inside for the winter, I’ll probably have to go through it again. Keep lots of dechlorinator and test strips on hand. 

[Markp2483]

I had a similar issue with my patio pond.  I bought a hanna checker. That showed zero chlorine or really low 0.01.  I think there may be something else that causes false positives with normal test strips.     

[PluckyD]

On 3/5/2024 at 6:21 AM, Stef said:

Is there any other decoration or plant container that’s leaching?

The only common denominator is the tubs themselves.

 

On 3/5/2024 at 9:08 AM, Markp2483 said:

there may be something else that causes false positives with normal test strips

I agree this seems to be happening. My only concern is that whatever is leaching might not be chlorine but it’s still causing damage to the inhabitants. I suppose the only hobbyist way to find out is to put creatures in anyway?

[JMC]

@PluckyD and @Stef sorry to revive an old thread but I have had chlorine suddenly show up in my outdoor tub. 
 

It’s a 100 gallon Rubbermaid. It’s over a year old. When I first put fish in about 12 months ago they did fine for a few weeks and then over a month or so they died a few fish at a time. 
 

I left the tub running all winter without fish and put in healthy (had been doing great in an aquarium inside for over 6 months) fish in the 100 gallon tub about 3 months ago. I also bought Aquarium Coop test strips this winter. The outdoor fish had been doing well for 3 months and the water has been testing good. 
 

I have always kept water level in the tub about 4 inches from the top. Over the last few days it has rained non stop and now the water level is about a quarter of an inch from the top. Also sadly about 50% of my fish were dead.  I tested the water with a test strip and it was:

Nitrate-0

Nitrate-0

Hardness(GH)-150 (Hard but normal)

Buffer(KH)-180 (High but normal)

pH-7.6

Chlorine-3.0 

 

I couldn’t figure out how rain water could spike Chlorine from 0 to 3 when it was only rain water that was added (at most 20% water). Then I read this thread and wondered if the plastic that has never really been underwater that is now underwater could be leaching chemicals into the water?  Was that what killed the fish last year (which again I never did a water test)?

 

Did you ever determine if your chlorine was coming from your tubs?  How long did you have to deal with your chlorine issues?

 

Thank you for any help you can provide!

[Stef]

Hi @JMC, sorry for your losses. In my situation, I too was using the multi test strips and getting high chlorine readings. There’s another post on this forum that mentioned the sun/daylight was causing an interaction with the chlorine test pad. Once I dipped the strip and immediately brought it inside to wait the 1 minute, there was no chlorine. If I leave the strip outside, even if it’s a cloudy day, the strip registers chlorine at 3.0.
 

I did not have fish loss. I am keeping comet goldfish and a koi. 
 

Is there any other plastics (plant baskets) or decorations in your tub?  
 

Try testing at night or quickly bring the dipped strip inside. I hope this method gives you zero chlorine too. 

[JMC]

@Stef thanks for the reply. I put in enough Prime for 50 gallons right after the first test. When I tested 7 hours later (and after dark) it tested 0 on chlorine. 
 

I’ll test again tomorrow in the daytime to see if the “chlorine” comes back when it’s daytime. 

If the chlorine does come back in the sunlight then I guess I’m back to trying to figure out what’s happening with my fish.

Thanks again for the advice. 

[PluckyD]

@JMC Sorry to hear about your fish 😞 

So, I actually just tested 3 of my ponds to give you a response, one was from last summer and two from this summer, and all 3 looked the same to my eye. I put them all against the chlorine test to show that they were above 0 but less than 3. However, I am now seeing @Stef post above and realize I am also testing out in broad daylight. This is my first time hearing about the impact of sunlight on the strips, and I really wanted to test it for myself but seem to have misplaced my bottle of test strips somewhere between the walk from the pond to my desk. 

FWIW, I keep mostly Miyuki Medaka ricefish in all of my ponds and they breed so prolifically, I wouldn't know if I lost some of them, but they all seem healthy as far as I can tell. I wonder if the rain water maybe washed some contaminants into your ponds somehow, or, just given the sudden sheer amount, caused some sudden change in parameters. Regardless, I hope it resolves even if you don't find the culprit. 

[PluckyD]

Found my bottle of strips and dipped it into one of my tanks that hasn’t had a water change in weeks (so no chlorine) then took it outside. I can confirm that sunlight (UV?) does result in a false positive for chlorine. 

[Static]

Hi All,

My personal experience with the test strips also lines up with @PluckyD findings.

Since realizing the effects of UV on the chlorine readings, I've taken all of my pond water samples indoors to test without any issues.

As far as I know, I haven't lost any outdoor Medaka's this season to water quality issues.

I started with 15 fish & now have a gazillion.

[johnnyxxl]

On 3/5/2024 at 4:16 PM, PluckyD said:

The only common denominator is the tubs themselves.

 

I agree this seems to be happening. My only concern is that whatever is leaching might not be chlorine but it’s still causing damage to the inhabitants. I suppose the only hobbyist way to find out is to put creatures in anyway

There are threads on here where the tubs are leeching chlorine into the water.  

[JMC]

@Stef, @PluckyD and @Static thanks for the help on solving my chlorine problem.  I too “have chlorine” whenever my test strip is used outdoors. I have not noticed any of the other parameters being different outside vs inside. 
 

I'm still not sure what triggered the fish to die off (will monitor the parameters better during the next big rain) but the die off has slowed down (only 2 more found in the last 2 days). The fish that are dying are Mosquito Fish. There are also Medakas in the tub that seem to be doing well, with no losses.

The Mosquito Fish and Medaka school together which was a surprise. I have only seen Mosquito Fish fry so far.  Maybe now that the Mosquito Fish population has been reduced the Medaka fry will be able to survive. 
 

Thanks again to everyone for the help.