Hi! I'm the only person who still comes here. Fortunately you're in luck and I can help you. Several things:
1) Your mash pH is too high at 5.7-5.8 unless you're treating somehow to bring it down. If not treating pH, that's going to hurt your efficiency in a big way. Add some acid (phosphoric, lactic, citric, vinegar, take your pick) and aim for closer to 5.4 as measured at room temperature, or 5.15 as measured at mash temp.
2) Volume measurements are key. If you're only collecting 12 gallons pre-boil, well... Brewer's Friend isn't right about this. You really want to collect at least 13 gallons, maybe even 13.5 gallons, and boil for as long as it takes to get down to 10.5-11 gallons. If your fermenters can't handle that much wort, then I guess start with 12 like you are. But collecting less wort also means collecting less sugar, so the efficiency falls as a result.
3) Striking with 9 gallons and sparging with 8 gallons also hurts your efficiency a bit as compared with the recommended 10 gallons strike 7 gallons sparge. With this, also, IF you are batch sparging, be sure to collect every drop of first runnings before adding the sparge water. This will maximize efficiency. IF on the other hand you are fly sparging, nevermind, except you should acidify your sparge water a bit then. With batch sparging, pH isn't important, but fly sparging it is.
4) It's an IPA, and with all the hops in there, you're going to lose some volume of wort which reduces efficiency a bit as well.
5) Finally, how's your crush? Do you mill the grains yourself, or does somebody else do it for you? LHBS's are notoriously HORRIBLE at crushing malts. Well crushed malt should have quite a lot of flour in it, with each kernel broken into 6-8 pieces. IF not crushed to that extent, well, start crushing it to that extent, then your efficiency will increase by about 10% on your next batch brewed that way. This should be number (1) above, but I'm too lazy to move it now.
All in all, any wort you lose is sugar lost which is efficiency loss. Make sure you minimize dead space and collect all your wort. Don't let any go to waste at the bottom of the mash tun. That's how I improved efficiency over time, learned to do all that.
Along with (2) above.... you could also increase efficiency if you were to extend the boil to say 90 minutes, 2 hours, 3 hours, whatever, by sparging a lot more than 7-8 gallons but maybe go 9-10 gallons and thus collect much more sugars and just boil off all the extra water. That's another option.
So..... just a few ideas. If I can be of further assistance, let me know, I'll be here every couple days to monitor the complete lack of traffic. Cheers, good luck, happy brewing.
