I want to run two tanks of the same sump

[Boby-reefs]

I have an existing 25 gallon tank and I’m about to add a sump..... my question to you guys is ..would adding another 20 gallon tank on the same sump would the bacteria be enoughfrom the existing tank for the other tank and I’m planning on using cycle sand and rock

pfa

 

[andrewey]

I would make sure the second tank is finished cycling and stable before plumbing them together. Let it go through it's diatoms and all the new tank uglies. Make sure your sump is large enough to handle drainage of both tanks. Make sure if the return on one gets clogged/reduced flow, you can't overfill that tank with the larger sump.