Tunze and JBJ get good reviews - i have a Tunze (old), a decent chiller will set you back at least 800-900 dollars, and they do cost a bit to run, even energy efficient models. Not to get in an argument - but the species in your tank are from area with water temp at 80F roughly. Secondarily, most
LFS keep tanks at 79 roughly. Lowering the tank temp below nominal temps for species most likely results in compromised immune system, which is more of a potential issue than pathogenic spread at a certain temp. Last article i read on fish patogens - shows a range of pathogens that proliferate at a significant range of temperature.
Below is disolved oxygen water table - not enough difference of 5f to affect fish (74f to 79f).
Water Temperatures Degrees ° C
Oxygen saturation in mg/l
Minimum oxygen requirements of fish (mg/l)
05° C = 41° F --- 12.8 mg/l --- Minimum 9.1 mg/l
10° C = 50° F --- 11.3 mg/l --- Minimum 8.8 mg/l
15° C = 59° F --- 10.2 mg/l --- Minimum 8.3 mg/l
20° C = 68° F --- 09.2 mg/l --- Minimum 7.8 mg/l
25° C = 77° F --- 08.2 mg/l --- Minimum 7.4 mg/l
30° C = 86° F --- 07.5 mg/l --- Minimum 6.9 mg/l
Just my opinion - but you could raise temp to 79F, not have to purchase a chiller, and disolved O2 is not an issue at 79F. Again just my opinion.