Moving fish from unhealthy tank

[Loribw]

I need advice! My 55 gallon tank has been overrun with algae and some sort of strange black “floating dots”. (I was gone several months and the caretaker didn’t care for it as I would have) - anyway, I want to completely clean the tank. I haven’t cleaned the sand, etc in a couple years. My question is, which would be worse....moving the fish without any of their current water into the newly cycled temporary tank, or moving them with some of their current, contaminated water? I don’t want to contaminate the new water.....

 

[ZxC]

If the water source's are similar, move the fish into the newly cycled tank - Test to ensure no ammonia spike.

Then tackle the cleaning!

 

[m.j.gomez]

Hello, check water parameters. Ammonia 0, nitrite 0, nitrates close, ph close & temp same then I would move fish over. If any of these way off I would reacclimate. I wouldn't use old water in tank. Hope this helps!

 

[m.j.gomez]

If the water source's are similar, move the fish into the newly cycled tank - Test to ensure no ammonia spike.

Then tackle the cleaning!

Sorry @Z×C: basically said same thing you did(middle of move & spinning!!!!!).