New betamarine owner

Most marine diesels max at about 3000 rpm. Based on Beta's specs for the BD722, max rpm is 3600 rpm. Was this under load or in neutral? A diesel should not be run at high rpm unless under load. When running your best rpm is probably between 2500 and 2800 rpm. You also probably won't gain more speed past this - just dig a bigger hole in the water and burn more fuel. Reserve max rpm for short runs when you really need it.
I'm not sure about the glow plugs as I've never had a diesel with them.
If you smell a lot of diesel combined with the advice to remove 30 year old steel tank I suggest you have that work done asap. Unless you have spilled diesel fuel while changing filters or bleeding lines there should be no diesel smell. A diesel is a closed system with injectors and the only openings the engine has to the atmosphere should be the tank vent and the exhaust. As I write this I am sitting at the salon table within 6 feet of a Yanmar that has no smell whatsoever.
If you're not sure about the operation of your diesel get a good book like Calder's book (shown below). It might be a good idea to pay a good mechanic to spend an hour going through your engine and systems on the boat to learn how to operate them properly.
Brian

I removed the (likely original) aluminum fuel tank in my 30 year old boat, as I figured it should be checked / cleaned. Lucky I did. it had pits on the bottom, where it sat on a wood frame. I was able to dig small holes in the tank with a screwdriver. It had been leaking somewhat, as the wood smelled heavily of diesel.

I replaced the tank with the new 19 gallon moeller poly fuel tank (around $150), and it came complete with the sending unit. I think it is a no brainer to replace the old tank, if you can get at it. Even removing the engine is not a big job. Just label all wires, and don't adjust your engine mounts, so the alignment will still be good.

I now have very little worry about clogged filters, and even water (my racor never has any in it) for a few years, as the tank is so much cleaner than an old one. Don't get me wrong, I still change filters, etc, but thye will be much less fouled than if I had a bunch of crud in the old tank, getting stirred up with every big wave you hit.
While i had the engine / tank out, I took the opportunity to clean / sand and paint the engine compartment, and the engine itself. It is so much better to have it redone. Can see leaks easily, and keep everything clean.