Water Changes

[Raswank]

Would there be anything wrong with doing a 40 gallon water change on a 90 gallon tank once a month? 100 pounds live rock, 3 inch sand bed, Many corals (not overcrowded) 3 fish.

 

[Dubbin1]

Thats a pretty good size water change but it should be fine.

 

[LOTUS50GOD]

you would almost see the same effect if you did 2- 20 gallon changes....

lets just say your nitrate is at 20... and you did a 40 gallon change... which is 44% of your total volume.. you will reduce your nitrate to 11.2

If you did a 20 gallon change that is 22% which would reduce your nitrates to 15.6 then another 20 gallon change would bring you to 12.1 nitrates

You will see a greater change with the larger water change, but not enough for a test kit to really tell you. You should match temperature and salinity as close as possible when doing such as large change.

 

[Raswank]

Thanks for your responses

 

[Wiskey]

I don't think it would be a problem, but if you are looking for a water change regimine I think you would be better off doing 20 gallons every 2 weeks, rather than 40 every 4 weeks.

Whiskey

 

[Raswank]

Thanks for all your help. Here is my other question. I usually RO/DI 40 gallons into my 44 gallon bucket. Put my mag 5 pump into it. Let it circulate. Add the required salt. Let it run a few days with the top a little open, or even closed. But I always get a little brown ring at the top of the water line in the bucket. What's up? All parameters are fine.

 

[Dubbin1]

What kind of salt are you using and is the bucket clean?

 

[Raswank]

Instant Ocean, brand new Rubbermaid 44 gallon bucket commercial strength. Cleaned thoroughly

 

[Wiskey]

I would not be too worried about a little residue, make sure your mag 5 does not have rusted screws though. I get white residue every time I mix up new water. I read an article on just what this is at one point, I don't remember seeing anything about brown residue though. Perhaps somebody can tell you what the brown color means.

HTH,
Whiskey

 

[Raswank]

Thanks it is a brand new Mag 5. I am just wondering if it is because of contact with air. When the Mag 5 is pumping it is pumping a lot of water and causing a lot of waves on top of the water. I would wonder if it causing an air exchange on top, causing a little brown residue on top. I don't know but thanks everybody.