Time to change food?

all five of them at the same time? are they getting into some other "food" source?

have they been tested for giardia?

Innova Puppy and Evo were too much for Kaiser.  He rarely had solid poo and I fed a lot of pumpkin to him in order to firm things up.

I've found that he does much better if I feed him a food that has sweet potato, as SP is a great source of fiber (to add bulk to the stool).

I switched both of the dogs and they now have much better/firmer/more consistent bowel movements.  I rotate between different brands such as Taste of the Wild, Natural Balance, California Natural, etc. -- my only "rule" is that I want it to have a good amount of sweet potato in the ingredients.  If I don't do this, it's back to feeding pumpkin.

I fed Luke nothing but Evo for three years and he looked fantastic on it -- his stool was mostly fine but occasionally soft.  Kaiser just couldn't handle it at all.

I would switch - it's probably too rich for their tummies.

If they've handled Evo just fine before this, try a round of Safeguard.  It's a bit pricey for the all the dogs (sorry), but it will get any possible bugs with the exception of one tapeworm they most likely don't have (and wouldn't cause this symptom anyway).  this includes Giardia, which is showing some resistance to the go-to med the vets typically give instead.

Safeguard is available over the counter.  Be sure to do all three days.  Then repeat in about seven days from the last treatment.  Finally, about a month from that treatment, repeat.  You won't have to do any other wormer other than HW during this time.  I don't recommend using Heartgard "plus" for instance.  Interceptor is fine.

You do want to treat your dogs.  The bug takes a while to get established sometimes if it's a sneaky, drug resistant type, but eventually unfortunately you'll get some symptoms in one or both of your own dogs.

I won't hurt, and it would definitely help, during the first round and second round, to do a period of bland food until the intestinal tract has a chance to fully repair.  A good human quality probiotic will help too - look for one in the refrigerated case of the health food store with a guaranteed CFU of acidophilus of one billion plus.

After things settle down, you can explore the possibility that they just need a simpler food - the dairy in Evo can be a real irritant during times of GI stress. 

Good luck!  Kind of a stinky time to, well, have stinky things happen. 

Safeguard is one of the safest meds out there.  It's approved for pregnant females and puppies as young as, I think, two weeks old.  It's got no contraindications that I'm aware of.