Jump to content

Shrimp tank woes/old tank syndrome/chlorine spike


Recommended Posts

Shrimp tank woes/old tank syndrome/chlorine readings 


I have an established 20 gal tank of 3 years that I converted into a shrimp only tank for my neocaridina shrimp about 2 months ago. I also have one bristlenose pleco and a mystery snail. 


In the past two months, I have added live plants such as hornwort, Christmas moss, Java fern and Anubia. 

I have inert substrate  

My water parameters are currently as follows:

72 degrees

GH 8

Nitrite 0

Nitrate 25

Chlorine 0.8-1.5 (without prime)

KH 4

pH 7

TDS 415


I have very hard well-water, so I use an RO unit that I remineralize with Shrimp mineral GH/KH+.  I’ve been slowly trying to remove 5% water 2-3x a week and replenishing with new water. 


About a month ago, I started noticing KH and pH drops. I added a small bag of crushed coral to my HOB filter. I also should add that I added a sponge filter for extra filtration and oxygen. I started to notice that I would get chlorine readings on my test strips almost every morning or every other morning. I would dose the tank with prime and it would register as 0. I don’t understand the chemistry enough as to why chlorine would show up in my tank as I do not add any untreated water.  Could it be the crushed coral?  Is it old tank syndrome combined with crushed coral? I have removed the bag of crushed coral in the meantime. 


I have lost several shrimp in the past two months, but currently the shrimp have been doing well - several berried and I see shrimplets, and my mystery snail had laid many clutches, but the chlorine readings worry me and I end up dosing prime directly into the tank whenever I notice it.  But, if I’m not in town for a period of time over a few days, I’m worried that the chlorine levels will rise and I will come back to the entire colony being wiped out.  

thanks in advance for any insight 

Link to comment
Share on other sites

Thanks!  I have been adding prime, to all water before I add it to the tank. The weird/unknown thing to me is understanding why I get chlorine readings at all once the water is in the tank. But, I continue dosing to the tank as needed. My issue is that I test it every morning and most mornings the test strip registers some chlorine, so I add more prime and then it goes back to 0. 

Link to comment
Share on other sites

On 6/27/2021 at 5:56 PM, Moomar said:

We have a water softener, so I have been using an RO unit.

Most RO units cannot effectively remove chlorine/chloramine.  You should dechlorinate using one of the “expensive” products (Seachem Prime, etc.)  or this can be done with plain old vitamin C (ascorbic acid).

On 6/27/2021 at 3:05 PM, Moomar said:

But, if I’m not in town for a period of time over a few days, I’m worried that the chlorine levels will rise

The chlorine levels will never rise (without the introduction of more chlorinated water), in fact - the opposite will occur.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...