I bought this one a few months ago, it worked great. Superior Pump 91250 1/4 HP Thermoplastic Utility Pump, Black https://www.amazon.com/dp/B000X05G1A/ref=cm_sw_r_cp_api_glt_fabc_AV1R3KRZCNK7MRC6DWN7?_encoding=UTF8&psc=1
They'll just take some of the pumps from off the shelf. It'll be fine..
Mine I'm not sure exactly it's gph but it's pretty high. What's your system look like? Do you have any filtration? I'm sure you're pump is fine, a little poop in the water in normal.
https://smile.amazon.com/gp/product/B00ANFXKM2 like this?
https://smile.amazon.com/Superior-Pump-91250-Submersible-Thermoplastic/dp/B000X05G1A
or this one is more like the one you found.
first i'd try to elevate the tank and just drain it passively, set up drip lines to connect to the barrel(s)
Just FYI designing pumps is a little more complicated that just GPM. depends on the height difference of the inlet & outlet (z), size of the inlet/outlet, and how fast you want to drain water (derivatives for v and p). Bernoulli's principle. Water pressure in your pipes is likely around 50 psi or 115 feet, and that 1800 gpm pump says 25 feet. 25' of pressure is likely a good number. my drip lines use ~50' and it's probably too much.
if you use a pump, ya gotta make sure it doesn't pump air or it'll break.
This ¼hp superior pump from Amazon and this Dernord spray ball work great for me.
Since I'm running pbw and sanitizer and everything through it, I sprung for the extended warranty thing on Amazon, it was relatively cheap.