The algae could be a couple things.
1) yea that's a lot of fish that poop a lot, especially tangs and angels who pick at the rock all day. That could easy result in detritus build up and cause algae.
2) filtration may not be large enough for your tank? What are you using for filtration and how many in tank powerheads do you have?
You will definitely need to upgrade to a sump, the bioload simply cannot be removed with what you have.
Reduce fish or up your filtration or your problem will only get worse. Not saying its impossible to have a fresh water filtered reef tank...but it is a ton more work.
No you don't need to drill at all! Thanks to some maniac who came up with these things! They are pretty awesome actually, and saved my tank when I first started. I had a canister and it was so bad with algae. You can easily make these too.
I'm not sure what does and doesn't ship to Canada, most likely though since we haven't gone to war with you yet lol. If they don't sell any to Canadians you could build one easily. There are plans for PVC versions (though not as attractive)
As far as crashing, that's just all up to how well you clean your filter and how often. More than likely you will have mass algae growth.
Well they just don't seem appealing but are majestics hard to keep? because I think I got way over my head with the koran and what about the asfur angelfish?
You already asked about the asfur remember, you'll need a much larger tank to keep it healthy.
Even if they were like freshwater oscars and could live in a smaller tank they still poop more than most fish out there. Your gonna want to really upgrade your filtration big time if you are going to try to keep these guys.
Otherwise I don't really know what else to say besides get a bigger tank
Is there any way to wean a angelfish off coral? because so far my koran devoured a zoa colony and is attacking a clove polyp colony same with the Singapore angelfish
Yeah if there was a way to train fish not to Munch corals that eat them in the wild we would all have reef tanks with Picasso triggers lol. It really does suck that some of the coolest ocean fish don't do what we want. Any fish trainers out there? There's a market for sure.