A skimmer doesn't have to cost a lot to work well. Mine was used and I think I paid about 40% what it would have retailed for. Several of your fish are going to outgrow your current setup and their current tank mates but I suspect you might already know that as its already happening. I've never owned a porcupine puffer but the snowflake will eventually be able to eat many of your other fish so I hope you have a plan. You've got just as many fish in your current system as I have in my 240gal system so I'm not at all surprised that you're having nitrate and phosphate issues. My system does quite well with a skimmer rated for 400gal with a similar fish list so you might want to consider that when you decide to upgrade.

Yeah the porcupine puffer will only be moved if he gets too big. The snowflake eel however is planned to be moved to a tank downstairs already before he gets aggressive and eats other fish.

I do like DIY but I'm now wondering about a denitrator coil, I might aswell build one of these along with the pvc skimmer. Do they work? The sound so simple to build just wondering if anyone has built one.

Give the algae scrubber a try man, you won't regret it.

nitrates
 

i just finished building 2 of them.i won't really know if they are working properly for a couple of weeks.i used 2 ' of 3" pvc pipe,drilled 2 -1/4 " holes on the top for an inlet and outlet and 50' of 1/4" tubing(you don't quite need it all)after a time of coiling the tubing in the pvc(takes time and patience as well as a few attempts without pinching the damn tubing) ,i stuffed it with 10 plastic pot scrubbers bought from the dollar store.the end of the tubing leading from the top i put a micro ball valve to control the flow,and the other hole i stuck in 3' of tubing about a 1/2" in to drain back to my tank.for the next 2 weeks i'm dripping about 2 drips per second and will slowly increase over the next couple of months

Ok gonna do the algae turf scrubber on the pipes going from tank to sump will be easy pesy.