OK, a couple of things with mangos.
I've made single source mango melomels before (I live in So Cal so we get several varieties of mangos here) and mixed fruit mango melomels (with peaches and nectarines).
I don't use pectinase. If you're using mangos, peaches, pears, nectarines, etc. just be prepared to let them sit for a while and clear. The fruit turns to mush and is just a mess. I don't worry about it. Pectinase will not help clear your must if you have not heated/boiled it to a point of setting the pectin in my experience. If you're worried about clearing you can use some grape tannin up front to help clear, usually about .3 - .5 tsp per gallon is sufficient for flavor, structure and to help clear.
I stripe peel about 1/3 of my mangos (use a potato peeler and take about four stripes per side off the fruit to get a little astringency from the skins) and completely peel the rest. I just dump the seeds in the fermentor with the rest of the must. I generally go 3 - 4 lbs of fruit per gallon of final volume so for a 6 gallon batch my minimum would be 18 lbs of mangos (if I'm just using mangos) and 24 lbs or more at the top end.
When doing these kinds of mels, I always go in a large fermentation bucket so I have plenty of room to aerate, add nutrient and stir the living crap out the must. You'll also want to punch down the cap of fruit that forms several (6 - 8 or more) times a day. I don't normally mention this part, but at the mead festival several people asked me about melomels, and two of my Zinfandels that I brought, and what I do with the fruit that floats to the top. I don't normally think about this because I make wine and punching down the cap is just part of the regimen, so I just do it by rote. Thanks to Ken Schramm for pointing to me and asking me how many times a day I punch down to set it in my mind that it is part of the process, and not just innate behavior.
I made a peachy-cot (peach and apricot) mel and used R2 yeast by Lallemand, it was great. But, for mango I prefer 71B or D47 with a preference for 71B.
So digging back a ways here's my six gallon recipe:
18 - 24 lbs fresh or frozen mangos - (if fresh 1/3 stripe peeled, 2/3 completely peeled, all halved and seeded)
10 lbs orange blossom honey
6 lbs alfalfa honey
3 tsp grape tannin
H2O to 6 gallons
71B yeast (up to 4, 5 gram packets rehydrated in Go Ferm as per Lallemand spec)
6 grams DAP in must prior to inoculation
Place about half of the seeds in a sanitized grain bag and place in fermentor. Cover with a sanitized cloth and secure with a rubber band.
Balance your must to about 30 brix (1.13+ SG)
Punch down fruit and stir several times daily.
Add 6 grams DAP into must at end of lag phase (when the must just starts to foam from yeast activity)
Aerate/Oxygenate daily
Remove seeds after 5 days and seal the fermentor, and cap with an airlock
Swirl the fermentor daily to keep yeast suspended as much as possible
Let the yeast run to completion (somewhere around 1.030-1.037 SG, or 8.0 - 8.5 brix)
Rack to secondary
Rack again when stratification is obvious and it is looking like its clearing.
Be patient it will clear with time.
Hope that helps,
Oskaar