Conductivity rise

[Matt2609]

Currently I have T. candidi as the only fish. I have one pair where they regularly spawn, however, I've only seen fry once. I believe that it is because my conductivity has started to slowly rise.

When I had the eggs hatch a couple of months ago, which was when they spawned for the first time, my conductivity was about 155. But after I recently did a 20 percent water change with pure RO, it's been impossible for me to get my conductivity below about 400. Slowly after I've done the water change where I attempt to lower my conductivity it goes back up to just about 400.
The first time I did the pure RO water change it just lowered the conductivity and there was no trouble at all, and it worked just as it was intended as they spawned a few days after.
So I was wondering what could have made my conductivity go up all of a sudden?

I have not been doing anything in the tank other than making water changes and feeding the fish.

 

[gerald]

Ions in fish food, plant ferts, soluble minerals in rocks, residual salts in driftwood .... ???
Did you test conductivity of your RO output? maybe RO membrane is leaking?

 

[sasikan]

Ions in fish food, plant ferts, soluble minerals in rocks, residual salts in driftwood .... ???
Did you test conductivity of your RO output? maybe RO membrane is leaking?

did you add rocks, sand, leaves plants ,anything to the water?

 

[Matt2609]

My RO water has a conductivity of 6 as it has always been, and as I mentioned the only thing I've added is food and a ketapang leaf once in a while. And of course I've been doing the regular water changes.

The driftwood that I've got in the tank has been there for a little more than a year, and the same goes for the substrate in the tank.

 

[gerald]

Unless you feed them pickles and salt-cured meat, or have salty air in your house, I'm mystified.

 

[Mike Wise]

Do you feed live brine shrimp? If you don't rinse them, they will have residual salt on them.

 

[hedylogus]

how often have you/do you measure EC? what's the EC of your tap? it's not unheard of for EC to jump 500uS a week under the right circumstances. even if you originally filled your tank with pure RO water and perform a weekly 20% water change with pure RO, if your specific environment contributes even 100uS every week.......it would only take a couple of months your tank to top 400uS.

 

[Matt2609]

I feed them with frozen daphnia (I get rid of as much of the water as possible), FD black worms and newly hatched brine shrimps. And yes I rinse the brine shrimps a few times before feeding with them.

Normally the conductivity in the tank is about 157 and when I do the water changes this is what I aim for, and then when I've done the pure RO water change is drops to about 100, and then after that I just do my regular water change with a conductivity of about 157.

 

[hedylogus]

my post on Friday got me thinking.......the value should level off eventually. if you assume concentration is linearly proportional to conductivity (general true at aquarium levels), this asymptotic value is W(1-P)/P, where W is your weekly increase in EC and P is your percent water change with pure RO water. not sure this helps you, but just thought i'd share.

 

[Matt2609]

The problem seems to have gone away all by itselft.. I don't know how really, but after my latest water change (saturday) I haven't seen the previous rise in conductivity.
But still thanks to all of you for being helpful trying to figure this out