The Merger

[Saltinthedesert]

About a week away from combining two of my 29g tanks into one 75g tank. Species are friendly and temperature/pH compatible. 
 

I’m wondering what tips/tricks you have for this sort of transition. The only equipment I needed to buy for the 75g was a light and I have that. I already have a filter, new substrate, and heater that are rated for the 75 but they are being used so is there a way to move over things without buying stuff I’d only need for the week or two to swap?

I’ve heard that putting the old filter in the new tank can speed up the cycle process but I don’t want the old tank without it too long. 
 

Basically I’m trying to make the merger happen as smoothly and as quickly as possible without any unnecessary delays, but taking the time to do it right. Is it worth putting a small amount of water that comes out during gravel vac in the new tank to seed it?

Input and questions welcome. 

[lefty o]

if you dont want to move one of the filters over, best bet is to move some plants or driftwood over a couple days or more before you move the fish.

[FrozenFins]

whatever filter your using for the 75, move over to the 25 (unless the ones you are using for the 25 are the ones you are using for the 75, which in that case you can fill the tank up and plug in the filter the same day you add the fish) do that for 3 weeks, then when its time, tear down both 25s and use the sand and driftwood over to the 75 as well as the pre-established filter. You can then add the fish.

[Saltinthedesert]

Got it. Yes, the filter that will be used in the 75 (a Magnum Canister) is currently in (and admittedly overkill for) the 30. 
 

1 hour ago, James Black said:

whatever filter your using for the 75, move over to the 25 (unless the ones you are using for the 25 are the ones you are using for the 75, which in that case you can fill the tank up and plug in the filter the same day you add the fish) do that for 3 weeks, then when its time, tear down both 25s and use the sand and driftwood over to the 75 as well as the pre-established filter. You can then add the fish.

 

[Tanked]

I would move as much decor, plants, etc. as you can into the new tank including water from both of the 29s.  This adds bacteria and nutrients into the 25+ gallons of tap water already in the tank.

I would follow that by blending over a day or three the water between the 29s, the goal being to have two and eventually 3 tanks with identical chemistry.