FunClucks
Crowing
I've used 2 Quart size horizontal nipple waterers for grow out chicks from 3-4 weeks until about 6 weeks. After that they use a 5 gal horizontal nipple waterer in the run. I use two 5 gal buckets for up to 20 chickens, and they work fine. I have two different types of nipples, and they seem to prefer the orange ones, but will happily drink out of either. I've blocked line of sight so the low pecking order chickens can sneak a drink without getting run off the water.
One thing to consider, what are the dimensions of your tank? Is it a vertical cylinder? Could be that the pressure of the water at the nipple for the 30 gal vertical tank is significantly more than the pressure of the water on your 5 gallon waterers or especially the 2.5 gallon waterers. The weight of that much water pushing back on the nipple valve to keep it closed means the chickens have to exert more effort to peck open the valve and it probably closes more quickly. So they drink some, but don't fill up all the way because getting the water out is exhausting. Eventually they give up before they've gotten enough to drink.
To fix this problem but supply the same amount of water, consider using some type of rectangular bin or tub to supply the water. Or see if you can turn your 30 gallon cooler on its side? One example is below. That would give you the same volume of water (and therefore roughly the same time between refills), but layed out horizontally, so the weight of the water keeping the valve closed is comparable or less than the weight the chickens are used to from the 5 gallon or 2.5 gal bucket waterers. Keep the water height above the nipple the same as with the 2.5 gal waterers with the same type of horizontal nipple valves, and you should have happy chickens.
When I say bin, it could be anything with this type of configuration, I'd put the nipples about an inch or so above the bottom of the bin and mount it up on cinderblocks to be the right height above the ground for the chickens. Check the material the bin is made of to make sure it will not out-gass chemicals into the chicken's water. Polyethylene or HDPE is a better choice than some of the other plastics from this standpoint. Food grade white bins are a good choice because you know those won't out-gass. But these are the same critters that eat food that's been sitting in poop... I think I care more than they do.
Also here's the horizontal nipples that I've tried, they both work but it's easier for me to install the orange ones, and the chickens seem to prefer those. They look about the same to me, but I'm not a chicken. Hope you figure it out!
One thing to consider, what are the dimensions of your tank? Is it a vertical cylinder? Could be that the pressure of the water at the nipple for the 30 gal vertical tank is significantly more than the pressure of the water on your 5 gallon waterers or especially the 2.5 gallon waterers. The weight of that much water pushing back on the nipple valve to keep it closed means the chickens have to exert more effort to peck open the valve and it probably closes more quickly. So they drink some, but don't fill up all the way because getting the water out is exhausting. Eventually they give up before they've gotten enough to drink.
To fix this problem but supply the same amount of water, consider using some type of rectangular bin or tub to supply the water. Or see if you can turn your 30 gallon cooler on its side? One example is below. That would give you the same volume of water (and therefore roughly the same time between refills), but layed out horizontally, so the weight of the water keeping the valve closed is comparable or less than the weight the chickens are used to from the 5 gallon or 2.5 gal bucket waterers. Keep the water height above the nipple the same as with the 2.5 gal waterers with the same type of horizontal nipple valves, and you should have happy chickens.
When I say bin, it could be anything with this type of configuration, I'd put the nipples about an inch or so above the bottom of the bin and mount it up on cinderblocks to be the right height above the ground for the chickens. Check the material the bin is made of to make sure it will not out-gass chemicals into the chicken's water. Polyethylene or HDPE is a better choice than some of the other plastics from this standpoint. Food grade white bins are a good choice because you know those won't out-gass. But these are the same critters that eat food that's been sitting in poop... I think I care more than they do.
Also here's the horizontal nipples that I've tried, they both work but it's easier for me to install the orange ones, and the chickens seem to prefer those. They look about the same to me, but I'm not a chicken. Hope you figure it out!