Unresolved fish dieing off slowly

who knows this could just be the sign i needed to finally break it down clean it and then make my lion fish tank i wanted to do in the first place. well really i wanted a sea horse tank but thats a diff story

 

Damsels are the hardiest fish in the ocean, IMOPE. Definitely sounds like something went awry.

How large was your water change?
What is your salinity and how are you testing?
Did you test the make-up water to insure that the sg, ph, and temp were the same as your tank?
Did you test the RO/DI to insure you were getting zero TDS before mixing?
Did you allow the make-up water to mix and aerate thoroughly?
What type of container do you mix in, and have you tested for phosphates?

 

I would also get a second opinion on the water parameters.

Do you know the nitrates prior to using the RO/DI?
How big of a water change did you do?

My gut tells me it's the water change, why not sure. Too large of one that changed the water chemistry significantly, some type of resin on the new RO unit.

Lastly Damsels do not have to actually inflict physical damage to stress other fish to death. The posturing and body language is sometimes enough to keep a more passive fish from getting all the food it needs. Continued stress leads to disease or decline in health.

In a 55 gallon I would not have thought that would be a problem but it very well might be with Damsels.

I myself would do nothing drastic at this time, double check results, looks for incidences of complications from use of new RO/DI units on the net.

Do you have any corals and how do they look?

 

When did you add your last fish?

 

water change was 15% like my normal.
1.023 sg with refracto and hydro
temp was the same cause they stayed in the same room and had a heater SG was same ph i didnt check
the TDS meter read 0
yes i let it set for about 2 days (got caught up with school and work before i could change it out) had a power head in it keeping it moving
i do it in a 5 gallon homedepot bucket (same one i used for the longest of times, and a 2.5 gallon water jug that i got brand new from store and rinsed out with RO/DI water).
last fish added about 4-5months ago

 

I was thinking its the water change to, and I mean when I do a top off I put the rodi hose n the sump and top it off. I ran the rodi system for awhile befor I even used it to do the top off or water change
And no corals in it.

 

The 0.1 drop in pH shouldn't have had any dramatic effects, and 7.9 is fine; Also, if the 15% WC dropped it, that of the makeup water would have been low enough to cause shock for any fish that came into contact with it before it thoroughly mixed with the tank water. However, I find that highly unlikely. You would need to mix and test a new batch for confirmation, but I've used IO for years (when not using NSW) with no problems.

Anyway, here's a bump for your thread....

 

Those are very hardy fish. It has to be something related to the RO unit and the water change since those are the two factors that were different. I would almost narrow it down to the RO unit.....I would check other parameters of the RO water besides TDS....

 

When's the last time you calibrated your refracto? Mine got messed up and I was at 1.036 not 1.025 ... Lost a few fish before I caught it.

 

It was calibrated the day befor I had just got it in, and also tested with hydrometer and I havnt lost another fish since my clown a week ago.