What happens when a rated skimmer is too big

[grinder143]

I currently have an ATI Bubblemaster 200 . I have given up on the psk 2500 pump and was going to get a psk 600 to replace it . This being said I have it on a 120 cube , it is acrylic . Boy I hate that. Well I have been contemplateing downsizeing this to a 40 breeder. I think this skimmer would be too big for that tank but really hard for me to know since this is an older skimmer. At some point the 40 would be heavily stocked. I don't want to replace the pump if I really need a smaller skimmer. Any input on this would be helpful.

[syrinx]

I have used insanely oversized skimmers for years, without issues. You can always set it to skim drier. As long as the pump does not heat the reduced water volume too much, the noise level isnt to high, or you have trouble with micro bubbles you should be fine.

[grinder143]

I think I will replace the pump. Even if it were not to work well, it has no resell value with no pump.