I have a 85' round x 5 foot deep pond. I want some form of rock on the bottom.....but I heard gravel promotes alge and decaying matter on the bottom of the pond because it grows in the crevis of the rock? Im trying to keep it "somewhat" like a pool...and keep the bottom fairly cleaned out.

1. Would sand be the same or better to not promote alge growth? The put sand in large marina aquariums at the zoo's??
2. Should I or shouldnt I put any form of rock in?

You need something over the liner to hold it down and prevent punctures. I would not want rock directly on the liner IF it had any sharp edges at all.

Sand would have less surface area exposed than rock, but algae can grow just fine on my clay bottoms. Cleaner bottom than clay or dirt, though.

I wonder if any types of sand are pointy enough to cause liner problems.

This PPL Liner is almost puncture resistant. Not really worried about that. Its stronger then a swimming pool liner, and most of the pond is very deep..so puncturing it would be very hard to do. Im just wondering what would be better... Sand or no sand.

I would think that you would have a hard time keeping the sand in place unless the pond is relatively flat.

I would go with smooth river gravel if you can get it.

Im only putting it on the flat bottom. The sides are way too steep.

Pea gravel or stone with no points will out perform the sand which holds more nutrients and I guess you have a bottom draw since it is a liner to aerate or filter away nutrients as the liner removes the resourses from the earth to balance the pond and the growth of the fish and other tennants I refer to them as tennants for the reason that their natural resources that were left to them from the past were altered without ----------- Who can say at the alarming rate that our potable supply is tainted. This Forum in the year 2040 will be disscusing the proper way to install a liner and how to consrtuct a dome to repel the elements and to purify water for the tennants not to much fodder there Bob.

That surprises me Trava? I would think that more nutrients would fall in and grow within the cracks of peagravel or round drain rock? vs sand which would let alge grow on the top surface layer....but not down deep in the crevis and cracks between the rocks?

It is not a suprise Face some of the biological personel will give you some insight on how naturalE filtration and propagation takes place in rocks that have a flow oxygen and critters. good luck