Patty:
I used the Pup Grass and then ordered the Pet Zoom for additional coverage... I have to say that I won't use either for my next litter... While I like the Pup grass much better, the odor does stay within the grass. I rinse thoroughly, use diluted bleach and rinse many more times, then hang to dry. My litters are 7 and 8 weeks old now and the grass is starting t o pull away from the interlock underneath. I duck taped the edges and they chew the tape off.
I never got to use the Pet Zoom. I actually threw it away. The grass was much longer and as soon as I put it in the puppy pen, they all were able to pull strands off of it. I duck taped those as well ( I bought 2 smaller ones) and the puppies went to the middle and were able to pull pieces off.. I would consider using the Pup grass for younger puppies, as it is a tighter weave and shorter grass. If I had the one litter of 5 I think it may have worked. They all went to it right away. Oh I did like the pee pads underneath to absorb the urine... Good luck!

Idea... any chance you could put a piece of St. Augustine grass instead of the plastic grass and just replace that ??? Is there enough space to put water at the bottom for the pee & the water? Kindda a hydroponic type thing??? Just a thought! ??

what is st. Augustine grass? not sure what you mean with the water. In the pan under the grass?

St Augustine is the grass in our front lawn in Texas, it's very hardy for dogs.

The thought was to put real grass (instead of fake grass) in a pan of dirt/water. Seems that it would be easier to keep clean and wash out? Just a thought.

I have been intrigued by the idea of the soil-free Marathon Lite sod sold by dog. com for pups and small dogs. It seems to grow in a hydroponic mat.
http://www.dog.com/item/pet-a-potty-marathon-lite-sod/102231/
The one time I wanted to use it, they were out of it.
I think that you could order several, and the pups would be trained to real grass. No soil, so no dirt, no worries of heavy metals, unless there is more to hydroponic style grass than I know. I would tend to want to rinse it and let it dry before first use.