I like bubble algae are you fragging soon? Tank is looking great Adam keep up the great work.
I have a couple also around the house , one for the front room where my tank is and another that watches outside the house. I think I paid 45 ea for them and have a subscription for a couple bucks a month for a 7 day recording service that I can go back 7 days and watch all Video. Oh and my kids hate them?
make me a custom basket to hold 3 8x8x1 marine pure blocks. This should free up some space in my filtration compartment while increasing surface area for microbial growth.
Tank looks great -
IMO - 3 blocks is overkill - I overdid it with a similar product (400g amount of media on a 75g system) and once it got going I struggled to keep any N03...starved a bunch of corals...and have battled a P04/N03 imbalances. For your size tank 1 is more than enough. Save your money and avoid the headaches.
2 cents~
With the way your tank is looking, I wouldn't fret at a bit over taking a cubic foot of LR rubble out of the sump. It's only providing a small percentage of bio-capacity that 1 block will provide. It's really non-intuitive...
Regarding the bubble algae, in a tank this size, I would definitely do multiple waves of manual removal before risking a "rouge crab". It's fairly easy to pick them loose and siphon them out...and don't fret over "popping them will spread them". It's way overstated...besides don't crabs or fish eating them "pop them" lol. Just siphon the pieces as best you can. http://www.reefkeeping.com/issues/2002-02/hcj/feature/
Regarding crabs, you just don't know if they will (i.e. eat sps) or not, and they can be hard to get out! I'm not saying it's a high risk that you will get one that eats coral, just saying it is a real risk.