Techniques for water change on large tank

**zfarsh** · 05-18-2011, 06:27 PM

Hi there,

I have a new 75 gallon tank. It will be planted with play sand substrate, and have Fancy Goldfish / bristlenose Plecos, Eheim 2217 canister fiter, and and Aquaclear back-up filter. That said, i want to know how people do water changes on such large aquariusm, say i need to do a weekly 25 - 50 % change (depending on final load of fish)? Honnestly, i wanted to use a hose and tap water, and only after to add the Prime to the aquarium, but i dont know if that would kill the good bacteries even if the fitlers are off. Otherwise, how do you handle such a large change? Thanks in advance.

**DrNic** · 05-18-2011, 06:39 PM

In my 75G I do water changes the same way I did in my smaller tanks. A python or some other siphon system is really a must for a tank this size. My order of operations is;

Connect python to sink
Drain tank 25-50%
Stop python
Add Prime and move plants if necessary
Turn on python and refill tank

It shouldn't bother your bacteria when you change the water and odds are even with a 50% change the filter will stay running and generate a waterfall on one side of the tank.

Using sand in your tank you might want to put a bucket under the syphon output in the sink to catch any of the sand you might pickup.

**Brhino** · 05-18-2011, 06:43 PM

I do the same as Dr Nic although I do shut my filters off while I change the water... in some cases the water level drops below the intakes so for me this is a requirement.