That's a standard fluorescent bulb on a pretty deep tank. (I have a 37 also.) I'm not sure abou thte mushrooms or GSP unless you can get them pretty much all the way to the top. The other problem with a 37 is that you're pretty much stuck with 24" bulbs in a 30" wide tank, so there's 3" on either side of the tank that isn't getting much light.
Coralife makes a two bulb standard wattage T5 fixture which would be a huge step up for not very much money. I picked one up in Virginia Beach for about $30 to replace a single bulb HO
strip I took off my 20L freshwater to supplement the 150 HQI on my 37. (The metal halides alone were too white, plus I wanted to supplement on the deep tank.)
This is the fixture I got:
Aquarium Lighting Fixture Coralife Aqualight T5 Dual Linear Strip Fixture, 2X14 Watt, 24 inch
Here's the 30" version:
Aquarium Lighting Fixture Coralife Aqualight T5 Dual Linear Strip Fixture, 2X18 Watt, 30 inch
If you go this route and go with the 24", be sure to put it over glass (which you should do anyway). The expandable legs are flimsy.
This is the website for the store where I bought mine:
Pet Supplies, Pet Supply, Pet Dog, Dog Supplies, Pet Products, cat supplies, fish supplies, dog food, cat food, pet dog, Care A Lot Pet Supply
I looked and could not find it in their catalog, but it might be worth a phone call if it can save you some cash.