Reddit reviews SUN Aquarium Submersible Water Pump (420 GPH)

To be perfectly frank this recipe doesn't make much sense as an all-grain at all. If anything it's a relative of UJSSM, where grains are being added just for flavor, and are giving no fermentable sugars at all. I don't offer that to be cruel, good AG recipes are hard to find, just to say that wherever you got this recipe, I wouldn't get any more AG recipes from their. Here are the issues:

1. Almost zero saccharification of the corn and very little of the rest of the grain. You have just shy of 15 lbs of grain going into 5 gallons of water, 8.5 of which is corn. 8.5 lbs of just corn is a reasonable amount of grain for that amount of water, but a 3lbs per gallon ratio of grain to water is completely unworkable. If that much grain actually saccharified you would have something the consistency of damp clay. Keep in mind that polenta, which is just boiled corn, is 1 cup cornmeal to 4-5 parts water, that's enough for oatmeal consistency.
   
   You can solve this by grinding your corn. Cracked corn is truly godawful for sacch efficiency. Corn has the densest of all starch reserves for any grain, but it accomplishes that by having an incredibly organized and packed in starch reserve which cannot be pulled out lightly. I don't know why cracked corn is so ubiquitous in AG recipes, but that grind size is, without exaggeration, several hundred times larger than what is workable by enzymes and boiling water. Whiskey; Technology, Production, and Marketing has the numbers on grind size but if you need proof go buy a lb of cornmeal and make polenta. It's the exact same species of corn (dent) but finely ground. Cracked corn is likely so popular because its cheap (less than 10 for a 50 lb bag at any feed store) and seemingly ungrindable (no brew store will ever grind corn for you because brew stores use either rolling or hammer mills which crush, and corn don't like being crushed--I know microdistillers that can't grind their own corn because they are former brewers and accidentally bought a fancy rolling mill instead of plate or stone mills). Rest assured you can easily hand grind corn with something like this. It's labor intensive but that exact mill lasted me 3 years of hand-ground 50 gallon ferments.
   
   You can absolutely boil that corn, but it's not necessary, 190 strike water is fine IF your corn is ground. Neither boiling directly or striking are going to get you a real appreciable amount of corn sugar.
   
   
2. Terrible terrible conversion of pretty much all grain starches. That 20 lbs of DME is easily 2/3rds of your fermentable sugars by itself...and you only fermented about 2/3rds of your available sugars before the yeast quit. Either the starch isn't converting at all, or its partially converting but the beta phase is failing (which is a good likelihood as barley was pitched ONLY at 160f). The latter would explain why it passed the iodine test bit failed fermentation. You need to pitch both alpha and beta amylase to convert starch. Alpha breaks starches down into poly-saccharides, beta breaks polys into mono and disaccharides (gross but workable simplification). Alpha is happy from 150 to about 170, beta is happy from 140 to 155. Barley has both, so yoy can halve your barley and pitch at 160 and high 140s, or you can pitch once at 152. At 160 a good portion of your beta will completely denature leaving you with polysaccharides that are way to big for your yeast to eat.
   
   Sidenote: iodine should completely disappear with a good conversion. You should be able to add the recommended amount (everything will turn purple but not black) then shake for 30s at which point it should become such a light red as to be barely perceivable from the original color.
   
   
3. This leads us to retrogradation. I couldn't give you an established rate of retrogradation, but it starts just under boiling and goes until alpha comes in. I can tell you that 2+ hours is begging to retrograde. Luckily retrogradation is easy to solve. High-temp alpha is cheap and widely available and can be added while boiling. If you're dedicated to converting only with barley, add a little barley just after boil or strike, then split the remaining barley and pitch alpha at 160-165 and beta sub-150. Alpha will denature at sub boiling but it won't denature immediately, and will give you enough time to bring the temp down to alpha pitch.
   
   That being said you still need to bring temp down smoothly and evenly (I strike, give it maybe 15, then cool to temp in about 30 minutes). 2 hours is too long even with the above technique. This pump plus a little 1/4 inch copper coil is perfect for the job (I love these pumps, I use these little 15 dollar chinese pumps in my micrdistillert more than I do my "professional" microbrew chugger--which is an unmitigated piece of shit).
   
   This brings us to the last piece of the bad conversion puzzle. Your instinct to add backset in during boil is right, in fact that pretty much the obly reason to add backset. You need to adjust ph down to 5.5 at room temp. 7 won't kill your enzymes (because they aren't alive) but it will slow them down, and between temp and the relatively low amount of barley you're using, they beed all the speed they can get. Get a good digital meter, strips are way too inaccurate.
   
   A good conversion will have the texture of flat soda (and you can easily get 1.05-06 just with grain). The kind of thing that isn't thick at all but if spilled will obviously quickly turn movie-theater-floor sticky.
   
   
4. yeast pitch is a bit high, DADY is very rough and tumble but it prefers 78 and will make a much better whiskey (which much bigger hearts) at 68-72.
   
   
   
   Finally about equipment. A 10 gal pot is absolutely fine for cooking whiskey. You can get a big mash tun but it's going to extremely expensive for any size that's beneficial. You're much better off just doing batches and consolidating then in a big fermentor (and yes the trash can thing is disheartening, but unfortunately distilling is rapidly rising in popularity so a ton of people are trying to jump on the bandwagon and fleece people ready to start a new hobby).
   
   You can just add boiling water into a big fermentor and add grain but 1) you need all the boiling water all at once, you can't be cooling and then reheating, 2) you'll need to add some commercial alpha at grain pitch (the corn will clump otherwise), and 3) you should ferment on grain to make up for some list efficicency.
   
   The absolutely most efficient highest yield method that a homedistiller can do is boil the corn in the water for 2 hours (use a grain bag and false bottoms can be cheaply made), squeeze out the grain after conversion, then add 170f degree water back into the spent grain, squeeze out the grain again and then ADD THE GRAIN TO THE FERMENTOR (I have tested it and squeezing the grain a second time but still adding the grain to the ferment does in fact produce a marginal improvement in yield over both 2 squeezes no grain and one squeeze, 170f water, no secind squeeze and ferment on grain). But there is always a point of diminishing returns, like I said a 200f strike is plently efficient to be economical and while I could drive another 10% out, corn is much less expensive than time.

You're going to want something more like this.

The one you linked won't have good head height.