setting up a new(used) 125gal tank

The water isn't as important as the benifical bacteria that is housed in the filter media and the substrate. So using the old substrate and keeping the filters running to keep the beneficial alive by running the filters while the move is happening is more important.

So what you're sort of saying is the bacteria can handle that water change shock?

yes, just make sure it's de-clored water and it should be fine as long as there is enough bacteria in the first place, it would be just like a drastic water change is all

The water isn't as important as the benifical bacteria that is housed in the filter media and the substrate. So using the old substrate and keeping the filters running to keep the beneficial alive by running the filters while the move is happening is more important.

So what you're sort of saying is the bacteria can handle that water change shock?

The water isn't as important as the benifical bacteria that is housed in the filter media and the substrate. So using the old substrate and keeping the filters running to keep the beneficial alive by running the filters while the move is happening is more important.

Keeper is right.  Add tap water and dechlor (I actually perfer Prime) but any dechlor is good.  Get the temps close,  and let her rip!  If you can keep the filters running like whetfish said,  then that's a bonus as well.

You can fill up the 125 with all tap. Just make sure that you add dechlorinator and bring the temp up to where it should be. Once you transfer the fish over immediately transfer over any decorations and filtrations. You might see a small cycle, but you should be just fine.

Keeper

This is what I've done for years ...never lost a fish!! Even did it in 15 deg temp one house to another and all fish made it!!!Wilpir ;D

You'll want to make sure to use your old filters with your new magnum in concert for a while until the magnum picks up some good bacteria.

Thanks, I think the second method sounds good to me. I will hopefully get this going this weekend. I just need to get enough people to help me carry the 125 into the house from the garage. Now, all I have to worry about is the filtration. I have a used magnum that I bought with the tank. I don't know if that will be sufficient enough for the tank or will I need more filters?

My guess is that both will work...I haven't tried it Keepers way, I've heard of people doing it though.  In my method you won't restart a cycle.  So since you need to move both tanks you could...

1.) move fish and move filters to one 55(let's call this 55A) so they can run elsewhere (don't really need to run, but i like to keep them moving)
2.) empty other 55(55B) into buckets and/or drain and move the tank
3.) move water, fish and filters from 55A to 55B
4.) move 55A out of the way and set up 125(add substrate)
5.) Put water from 55B and any water from extra buckets in 125
6.) put in fish
7.) add tap/conditioned tap(whatever you normally do for a water change)
8.) add filters etc.
9.) post your tanks on gcca classifieds

I need to move both 55, since they are next to each other. And both have malawians in them so all the fish will go in together in the 125gal. So I would need to empty both tanks at the same time, so that I can move them and place my 125.

Keeper said that I can just fill the entire 125 with tap water and add chlrorine remover and that should be fine. How come some say use 50% of the existing water and some say to use tap water. Which one is the correct way?

I've moved tanks into the same place as an existing tank and it's pretty much a pain in the @$$ unless you have a lot of tanks to use as places to put the fish.  What I'd do is keep your filters running so as to keep good bacteria happy and use the same substrate so as to keep the bacteria associated with it.  Also this is assuming your two tanks have the same water conditions(You'd be the best judge of that). 

I'd move all the fish out into storage containers or one 55 that you don't need to move yet.  This way your fish are out of the way and you can get down to water moving business.  I'd say that you only really need to keep about 60 gallons(some folks will tell you less) of existing tank water, think of it as a 50% water change...if you do that regularly anyway your fish won't skip a beat. 

So...
1.) move fish
2.) move filters so they can run elsewhere (don't really need to run, but i like to keep them moving)
3.) get water out of tanks where you need to put the 125
4.) put 125 in place
5.) fill up half way with old tank water
6.) put in fish
7.) add tap/conditioned tap(whatever you normally do for a water change)
8.) add filters etc.
9.) post your tanks on gcca classifieds

One thing that makes this all easier is if you already use sponge filters... they are easy to toss into buckets with fish and keep the bacteria happy.

Hence I will need to move the 55 to put the 125 before I fill it up.

Do you need to move two 55s to put in the 125 or just one?



FYI this way is the hard way, but it will work.