Sorry to dredge this up again. I'm not trying to be LAM in my posting. 
Once this pond cycles, I'd like to add more fish. For a 75 gal pond, how many can I safely add? The guy in petsmart said I could put 10 in there, but that seems like way too many. I was thinking of adding 3-5 pretty little comets and helping them grow into 3-5 pretty big comets. Is that reasonable? Am I being overly cautious? Is there anything wrong with getting the comet feeder fish that are $0.24 as opposed to shelling out $6 for a little bit bigger comets?
The guy said that because of the evap factor (I'm having to add 15 gal every 3 days or so) that this is effectively like changing out the water, so it means the pond can support a few more fish. Is this true or is it so much BS?
Also, I really don't have a way to quarantine the new guys. I'm feeling a little guilt over that. Is this really such a big deal in a pond setting?
Thanks y'all!

Once this pond cycles, I'd like to add more fish. For a 75 gal pond, how many can I safely add? The guy in petsmart said I could put 10 in there, but that seems like way too many. I was thinking of adding 3-5 pretty little comets and helping them grow into 3-5 pretty big comets. Is that reasonable? Am I being overly cautious? Is there anything wrong with getting the comet feeder fish that are $0.24 as opposed to shelling out $6 for a little bit bigger comets?
The guy said that because of the evap factor (I'm having to add 15 gal every 3 days or so) that this is effectively like changing out the water, so it means the pond can support a few more fish. Is this true or is it so much BS?
Also, I really don't have a way to quarantine the new guys. I'm feeling a little guilt over that. Is this really such a big deal in a pond setting?
Thanks y'all!