[tang daddy]

trigger man has some good points.

K4's are not that powerfull as I have the equivilent of 2 k7's in mine and my 1in perc does fine, as for your powerhead under the rock it is not suggestable because if you have to clean it it could be a hassle to remove your rock work also fish at night like to sleep in caves so it could be a danger hazzard.

As long as the powerhead is not pointing to the torch it should be fine but if the bubbles on the torch are compressed then you should direct the heads differently pics would help.

1 last thing micro bubbles is not harmfull however very ugly IMO. to solve this there are a few ways put a micron bag on the return/overflow line, put more baffles in your sump or lastly use filter floss to stop bubbles.
The last suggestion about filterfloss is not very advisable as this can cause heavy nitrates and also have to be changed every 3-5 days.
I would redo the sump and add more baffles a pic of your sump would give me an idea of where the problem is.