Question about normal amount to pee - 3 kittens, 2 cats.

Hi all.  I have 5 cats now (ugh) the three kittens I rescued from a stray last summer,  and now the stray mom and the stray tom who I have since gotten fixed and ended up taking in as well. 

I have the cats on two floors, the parents upstairs and the kittens downstairs.  I've just been noticing the difference in volume regarding the pee clumps I scoop out.  For the three kittens some of them are huge and I would say there is nearly double the amount from the adult cats.  All the kittens are on wet food only, as is the (former) tom.  The mom cat is very small 8lbs and gets only kibble.  The kittens are 6, 8 and 11lbs.   Everybody eats, sleeps and plays fine.  

Just wondering what other people have noticed.  Some of the clumps in the kittens litter box are 5-6" across.  Then again I don't know if this is cause two of them have peed in the same spot. I kind of doubt it cause the box is huge.   I use Tidy Cat for multiple cats.  The kittens go through about a 20lb container a week.  The same amount can last me twice as long for the adult cats. 

I think it varies by cat.  I have a male cat (neutered) who pees the smallest clumps in the box.  My older girl pees medium sized clumps.  My younger girl pees HUGE clumps and she's the smallest of all three kitties!  My kitties also eat mostly canned food with water added, but they also get a very small serving of dry food spread out through the day.  Kittens generally tend to have higher metabolism rates, so they eliminate more often.  As they age, they go less.

Well, too, what goes in, must come out, in the case of moisture.  The cats that eat canned food will probably produce more urine that the one that eats dry food, unless the dry eater drinks a lot of water.