How much water to change?

[karlo]

We have a 400 Gallon tank at work and were talking to someone that might maintain this tank and one thing that caught my attention and was kind of surprised was the amount of water change he mentioned. He said he would do a 90% water change on a monthly basis and I was wondering if that is recommended and safe for the fish?

We still don't have any fish but were looking at getting about 50-60 Cichlids and that's what he said would need to be changed.

Too much or is that correct?

[sunkenmetal]

Well it is a monthly water change...

[eklikewhoa]

Water holds no beneficial bacteria and is just dirty water.

As long as the filters stay running and the new water isn't high in chlorine doing large water changes won't effect it much. I do 100% most of the time and that is done weekly, when I'm not lazy I like to do 100% twice a week.

[karlo]

cool, thanks

[troy tucker]

I don't do as much but I vac. the tank everyday. thats 5g to 15g everyday. with a 25% one a week. its about keeping it clean and you will figure it out.

[cu0ngsayz]

50-60 fish in a 400g? im surprised Q didnt clown on that.. ahhaha but yea once the filters have that bacteria youre ok with clearing the whole tank as long as you dont have water that contains high amount of chlorine

[AQUAMAN0306]

Here ya go 90% wc

[eklikewhoa]

LoL I just did a water change and that's how my fish were too

The MBU didn't like it too much though but the others are use to it. Once water gets low they all know to go to the areas with no sand and huddle together.

[TROPHS4LIFE]

90% yeah right who knows what treatments are being done too the water in the area i know they play with mine a ton and if i did a 90% WC my fish would be dead.............sure the bio is still there but if you change your water parameters too drastically too qiuckly then look out 30% twice weekly.................imo

[barberking12]

I don't do as much but I vac. the tank everyday. thats 5g to 15g everyday. with a 25% one a week. its about keeping it clean and you will figure it out.

same here i just vac out the substrate 2 times a week and a 50% wc

[eklikewhoa]

90% yeah right who knows what treatments are being done too the water in the area i know they play with mine a ton and if i did a 90% WC my fish would be dead.............sure the bio is still there but if you change your water parameters too drastically too qiuckly then look out 30% twice weekly.................imo

That's why there's a carbon bottle bro!

[TiAg]

Some sensitive fish like Rams don't do well with massive water changes. I do about 50% every 2 weeks on my 200 gal (running 2 eheims) and clean the media monthly. Waters clean, fish are happy - and I don't stress everyone out. I would think 90-100% is drastic and would only be done in an emergency.

Course thats just a mixed cichlid tropical. My discuss tank gets 10% every couple days and reef tank gets 10-15% every week.

[eklikewhoa]

if you are using prepared water for the rams that are close to the params they do fine. My old planted tank use to get 100% as well and I had apistos and such and the large water change would spark mad breeding.

[Darbex]

When I had discus I would do 50% twice a week. On my reef tank I do 20-30% every two weeks now. When I had a hi-tech planted tank with rams and such I never did a water change only top offs.