# Need Help Replacing Substrate



## HeXoM (Oct 5, 2010)

Hey guys, I have a 20 gallon tank that I started up about 4 months ago. I have black substrate that I want to change with caribseas fiji pink sand.
How can I go about doing this the best way in one day?
Will I go through a mini cycle afterwards?
Will my fish be ok in murky/cloudy water?
I just bulit a sump/refugium and I am planning on setting up once I get my overflow box next week?
Should I do it after I setup the refugium or the same day?
I really need some help guys.
I would really appreciate it.
Just want to do it right the first time instead of me guessing on how to do it.


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## bearwithfish (Sep 29, 2009)

HeXoM said:


> Hey guys, I have a 20 gallon tank that I started up about 4 months ago. I have black substrate that I want to change with caribseas fiji pink sand.
> How can I go about doing this the best way in one day?
> Will I go through a mini cycle afterwards?
> Will my fish be ok in murky/cloudy water?
> ...


so you are changing out 100% of your substrate? if this is correct you are really starting over again... while doable not highly recommended with fish involved... there are a few things you could do and i will toss them out randomly and others can chime in any time....

slowly replace a little of your substrate at a time working from one end of the tank to the other about 1/8th at a time with 2-3 weeks between each change

mix the two slowly about 1/4 of new stuff every 1-2 weeks

start a QT and monitor closely for the interim then empty tank and start fresh...

add current sand to fuge, let settle, add fish start DT over and add fish back later 

were it me i would likely mix them and just have more substrate... you are looking at losing all the established bacteria and such that have grown over the last 4 months and starting over... not impossible just not real good for the fish


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## Pasfur (Mar 29, 2008)

Replacing the substrate in a marine tank is a horrible idea, especially after it is established. Almost all of your existing microfauna live in the substrate, providing great stability to the system. I could not be more against this idea, based on the health of the system only.


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