pvc gate valve vs ball valve

[crimsoncoral]

OK I was under the impression a gate valve was easier to control flow rate than a ball valve. Is this the case? Also I found this statement at plumbingsupply.com and I'd never heard this before:
"We do not sell PVC gate valves due to their unreliability" -- are they really this bad? Thanks!

[Rin]

In my business a reliable valve has more to do with the manufacturer than with the valve itself. But I guess I can see where a good gate valve would be sort of tough to manufacutre if it had to be totally non-metalic. The seals on a gate valve tend to wear down, you have to turn them tight to maintain a good seal. After a while the plastic would give.

[organicreefer]

crimson,
gate valves probly arent reliable long term under higher pressures.....
but dont forget youre plumbing an aquarium and pressure is small to none;) rest assured they arent talking about plumbing a fish tank when they say they are unreliable.more or less youre gonna use a gate valve to regulate flow ,not shut it off under pressure.......
gate valves are better for fine tuning than ball valves,so they say.
my old etss has a gate valve at least six years old works great.jmo