WATER CHANGE ADVICE

I may be missing the point here, but it's not the cost that's worrying me it's the fact you've been recommended to do a 90% water change. Please tell me that wasn't all in one go. As far as I'm aware that much of a change in one go can do more harm than good.
 
Yeah it's not recommend, but a 90% won't do any harm as long as the temp, salinity are matched exactly. The alkalinity and calcium need to be close. I've changed out 75% or so of the water when I started using RO/DI.
 
The guy, who trust to a certain degree said that a larger water change on a less regular basis is more effective that more frequent smaller ones.

I might as weel tell you about the guy. He has been running an aquarium shop for 21 years and his original career was a chemsit, so he knows things.
 
Hes right if you have a high nitrate, phosphate, etc level and are trying to bring it down. However if your tank is stable and runs itself then you only need small water changes to replenish the trace elements along with dosing off a 2 part additive to keep the alkalinity and calcium correct. This is cheaper than massive water changes.
 
pH is keep in check by the alkalinity level, which is the waters buffering ability. If you don't have alkalinity and calcium test kits they would be good to purchase and make sure to get the liquid ones.

Anyway pH is not something that takes a major water change to adjust. Nitrate on the other hand if you had 20ppm and changed out 10% it would drop by 2ppm, where as a 90% water change would drop it by 18ppm.
 
I have a 150gal. fowlr tank and I change out about 40gal. every month. I use natural seawater from my local aquarium... Is this too much or am I doing ok?


rp
 
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