pressure washer to clean base rock

[wooden_reefer]

The background is that I made quite a lot of base (to be live) rock.

I used a heat gun to melt styrofoam in the middle, thus forming a mold, and poured my mix into the mold.

Now I have problem with bits of styrofoam embedded into the surface of the rock, just the sides where the mold was. A few of these bits are hard due to once molten styrofoam.

I think the best tool to clean this bits off is a pressure washer (most of them the rest I have to pick out manually). I probably would want to buy one eventually, might as well now.

First, am I making a big fuss? Is styrofoam toxic? I know that some people actually use it directly (not as a mold) and immerse it into a reef tank. They coat the styrofoam with a special (but still portand cement based ) cement. I don't know how it works out. It concerns me because when I heated the styrofoam it emitted an odor, like the odor in ironing permanent press shirts.

Second, those who know please tell me what pressure rating of a pressure washer is best, economically and functional, has the best chance of working well.

[Pbrown3701]

Styrofoam is non-toxic. However, once you melt it, it changes the chemical structure. I'm not sure if melted styrofoam is safe or not.

Regarding pressure washers, i have a Troy Built unit i got from lowes and it's worked great. Just a middle of the line model. I use it to clean the patios and such...

[sam1174]

If you're talking about expanded polystyrene (the kind of foam used in picnic coolers) it is toxic when heated. It emits cyanide gas, so I wouldn't recommend heating it. I guess you're already beyond that point, though. Regular old gasoline will dissolve the foam. People who work with composites will use expanded polystyrene to make a male mold and then cover the mold with fiberglass. After the fiberglass sets up, they drill a hole and pour gasoline in to melt the polystyrene. You could use gasoline to clean your rock, and then use the pressure washer to remove all traces of the gasoline. In fact, you could use alcohol to remove the gasoline, and then use the pressure washer.

Just a thought...