There is a debate in the water gardening world about rocks on the bottom of the pond. Now, we both know that this is a silly thing to debate when there are so many other more important things but hey - gardeners being gardeners, they'll debate and rant about things that somewhat - well - dumb.
And yes, if you want to clean the pond right down to the bare plastic, it will be really hard to do this with rocks there. Having said that - I note you don't have to clean right to the plastic. The stuff on the plastic is the good algae and we don't want to get rid of it.
For the plastic pond liner people, it is all about ease of maintenance. Nice argument but specious.
Water gardening cleaning is as simple as dropping the water level and hosing down the rocks. The force of a regular hose nozzle will float all the excessive organic matter out from between the rocks into the water where your pump (disconnect it from the filters so it is pumping directly out of the pond) will pump it onto your vegetable garden.
What stays behind is acceptable.
The root of this water gardening power-struggle is that a company called Aquascapes has come in - modernized the entire water gardening industry and made a lot of money in the process. They charge handsomely for their systems and installation and this annoys the heck out of water gardening landscapers who've been doing it the old way for quite some time. To be precise, it p**** off the established stuck-in-their-ways water gardening folks who don't want to look like they've been doing it wrong all these years.
Me. I don't give a fig which system is the easiest to clean. For my money - they both are and I've done both. I also don't care which system makes the landscaper the most money.
Let's even assume that those who build ponds both ways are right - they never have problems in their ponds. It isn't about which system is right or wrong, or cheapest or most expensive.
The bottom line for me is this.
I want a pond that looks real.
When was the last time you ever saw a natural water garden in the bush or swamp that had a black plastic liner installed by Mother Nature? That sat up there showing black plastic.
Black plastic on the bottom of a pond looks like black plastic. And it's ugly.
You want ugly?