shawn, i havent checked out ewests links which undoubtedly provide the info you need, but just thought i'd chime in on yer situation. first, if needed, tilled and compacted bentonite would be fantastic if your resources can handle it (maybe you have a good wholesale supply?). Regarding yer pond substrate soil, a formal lab test (sieve analysis) takes all guess work out of it, and will help you decide how much bentonite you'll need to shift your pond substrate to a clay dominant soil.
second, just a little about your dirt. Based on your test results, its interesting how much variation you have in pond area. How long did you let the samples sit in water after mixing and before taking picture? The one on left appears like a clay dominant soil, it�s the only one showing colloidal suspension. perhaps you can salvage excavated dirt from this area to add to the other areas. The others clearly settled out and are likely silt (plus or minus sand) dominant soils.
in general terms for anyone trying to identify what they have........sand, silt and clay are the three primary types of particles that make up most soil. A laboratory sieve analysis tells you exactly what percentage of each is in your soil. for a SWAG in the field, sand is obvious, you can see and feel the grains. clays and silts are trickier, especially silt soils, moisture conditions can make one seem like the other, but there are a few things you can try in addition to a water/jar test. (1) wet a handful of dirt (from each of your different areas) and make a ball in your hand, roll it around and twirl and squeeze out a thin thread. You have to work it a while, make it pliable before trying the thread. if its clay you can twirl out the thread a ways before it breaks, the more silt it has in it, the easier the thread breaks apart. (2) with the same moistened dirt, you can roll out a little cigar shape and pull each end. a pure clay will stretch (i.e. it exhibits plasticity), the more silt it has, the less it stretches, pure silt has effectively no plasticity, the cigar just breaks. (3) another quick way i can tell a silt soil is to place a small piece between top and bottom of front teeth, rub it a bit between teeth, (grit = silt) .....if its mostly slick....its mostly clay soil, if its mostly gritty.....its mostly silt soil.
needless to say sand and silt dominant soils leak, while the clay dominant soils dont....(o.k. they just leak REALLY slow)...few people are lucky enough to have pure clay (Brettski :rolleyes: ) and do fine if their pond substrates are mixtures of clay with sands and silts, but the clay HAS to be the dominant particle in soil.
Good luck shawn
