Large water change???

[Ihsnshaik]

I am wondering if it's okay to do a 80-90 percent water change in a 200 gallon tank. I have a 50 gallon sump with a sponge filter in it ( Just incase I need to setup another tank) and one inside my tank. It has an overflow system and was wondering if a large water change will impact my fish. My filter media and everything has been cycled and been running for 7 years on the same setup. I usually do max 50 percent water change but recently I been moving around some decorations and made my tank super cloudy. A lot of waste mainly.

I just want to know if its safe for my fish. I have flowerhorn/ midas/ red devil/ texas in the tank. All range from 2" to 18 inches.

 

[krichardson]

The fish should be fine as long as you can keep the new water temperature close to that of the discarded water.They may still be stressed a little but they should recover.

 

[ragin_cajun]

I do that all the time--I wouldn't think twice about it. Fresh water, plenty of Prime, no problem. I don't worry about temperature, either. I figure water comes outta the tap 72-75 degrees, I keep the tank at 79 degrees, they can deal with it.

 

[convict360]

Yeah if you can match water temps and dose with a conditioner it's fine, its basically down to that. If you can't match the temp you're at greater risk of changing the temperature drastically which you'd ideally want to avoid

 

[numbah84]

I agree with all the other comments here and in my opinion matching water temps only needs to be as accurate as them feeling similar to the touch. People don't give enough credit to what the fish can handle.

 

[boldtogether]

Sometimes, a massive water change and temp swing will trigger breeding and other good stuff.
I do minimum 60% water changes weekly to keep NO3 on a decline.

 

[DDK]

^ agreed, i drain the water till the point where the fish can swim comfortably

 

[Hoplo]

Nothing wrong with doing large water changes, just as long as you are doing the large water changes regularily.

 

[pperrotta]

Agreed with the above comments. Just be careful with certain fish that may be more sensitive to temperature swings. As long as your tank water is clean (free of excess ammonia, etc.) you should be fine. I do this sort of thing all the time with lots of different types of fish, never had a problem.

 

[viejafish]

I have been routinely doing 75-80% WC in my show tanks, and my fish love it. I don't worry about the small temp change as I fill the tank slowly and the fish has time to adjust to the new temp. But I am blessed with good tap water which is from well field and is only lightly chlorinated. If your tap water is from river or reservoir that is treated with chloramine, it may not be safe for you to do large WC.