Have yours been the oriental weather loach, M.  anguillicaudatus? A measure of my unfamiliarity is that I was surprised that the European weather loach, Misgurnus fossilis, isn't the one usually in the hobby. (Good Grief, there are maybe 51 species and subspecies of Misgurnus and there are loaches from other genus also called weather loaches!)

Was also surprised to see that they enjoy a vegetable component in their diet, which doesn't sound too different from guppies. While listening to a night game (go White Sox! Go Cubs!) it is kind of fun to amble around the fish tanks, popping out the insides of cook peas, crushing them to size and plunking them in selected aquariums. The pea shells either go to the snails and bristlenoses or to the small, jealous dog following me around. [Some dogs reason that if those strong scented flakes are going to other pets, they should go to me too. The dog of some friends of ours got a hold of a canister of flake food, chewed the container open and devoured everything in the canister. Come to think of it, probably operating on much the same logic, our daughter, when 2 or 3, was discovered glomming down small handfulls of trout chow like they were Cheerios! No problems resulted, though she had a decided tendency to swim upstream in the tub. ;) ]

There are play sands and there are play sands. Some of them seem to be great for fish tanks. Some sand can not go through the acid test (a little Muriatic or hydrochloric acid) because it has too much additional mineral in it. Conventional wisdom with sand or rocks it to dump a little of that acid on it (as you know - only outside). If there is a reaction - a little bubbling or fizzing - don't use it.

Some sellers have pawned off sands, which would be better intended for construction than for sand boxes or aquariums, because of sharp edges. Would using a hand lens allow one to see the edges of the grains?

Aquarists also are sometimes hesitant to use sand with plants, since the sand may pack too tightly for plant roots. Of course with loaches that bury in the sand, that might not be an issue. Just keeping the plants rooted is the issue. :) Probably you wouldn't have plants in the sand.

Could you use Java ferns with the loaches? Would the loaches nibble upon Java moss, hornwort or water sprite (great hiding places for guppy fry?

By the way, would guppy fry be at risk with larger loaches? Sometimes, given the guppy's proclivity for dropping too many fry, that wouldn't be a problem.

Some play sands from hardware stores or pool centers seems to be fine. It may have to do with how much rinsing a person is prepared to do or the local sources. I have been astonished by the seemingly high calcium content of pea gravel from local garden canters here in northern Illinois.

For more on that go to http://fins.actwin.com/search.cgi and search for play sand.

That is interesting, the addition of RO water. You are obviously more familiar with the use of this water than most first time visitors to Guppylog. Is your regular water supply quite high in mineral content?

So long as guppies are gradually acclimated to water of a pH of 8.4, they shouldn't be harmed. A lot of municipal supplies around here are buffered quite high so as to avoid leaching from lead pipes. The guppies don't seem bothered. And as biological processes get going, pH tends to drop.

I'm not so familiar with relative measurements of alkalinity. Is the 200 PPM alkalinity or general hardness or TDS (total dissolved solids) or something else? (Go to that FINS site and search for measuring alkalinity - whoowee!)

I think you are wise to add no more substances to that tank than you have to. I know of aquarists who are far more chemically aware than I, who do that, but moderation or abstinence in doing those things, is often wise.

It may be that the cloud will just go away. Glad to see that the guppies cycling the tank are doing fine - another reason not to tweak the tank unnecessarily. The cloud may just "go away" and I'd look for that first. What kind of filtration are you using?

Guppies, in terms of natural habitats, usually come from waters with an alkaline tendency. A lot of those places may have a rocky under layer (limestone?) which would encourage that. However places like Trinidad usually have much more rain annually (though sometimes it is seasonal and in cloudbursts). That would tend to dilute the water's overall mineral content. Certainly our Illinois well water and maybe yours would have more of a mineral content to it, so your seeking of a moderate level for your loaches and Loricariids usually shouldn't hurt the guppies.

There seem to be a couple of great aquarium societies in Texas. Houston has an active livebearer group and they helped in hosting the ALA convention on the San Antonio area a couple of months ago.

I had wanted to get to that or to the NANFA event in September in the Athens, TX area. http://www.nanfa.org/convention/2008.shtml
Having attended one national for the year, that will probably be about it, unless i slip into the IFGA event in Chicago, whenever the IFGA updates their web site.

Your state, huge as it is, has been/ will be a good area for several great aquatic events.

Please let us know how your tank turns out, how your guppies do and how the guppies and loaches get along!