Foamed Water Condition

Question
Karen,

I'm a 21 year from Australia keeping C.Frontosa, Electric Yellows/Blues and basic catfish (bristle-nose and Plecs), all in a 200L tank (the fish are quite small and I'm upgrading the tank very soon to a ~600L. I've been at it now for about 2 years with a high level of success in tank conditions, breading and general fish health. About a week ago i purchased a bag of 10Kg coloured stones from a reputable aquarium, after a considerable wash and 12 hour soak, i added to the stones to my tank. within a few hours i noticed the bubble emissions from my under-gravel had decreased significantly  and were creating a small layer of foam on the surface layer that dissipate quickly when touched. i have since done a 50% water change through a gravel vac and retained the water conditions using all the products i have for the last two years. the bubble emissions are now slightly larger but not to the size they were pre stone addition, and the foam (all though much less) still remains.

I've added stones from the same provider before with no such result, i have 200 yellow lab fry in holding nets inside the tank and all seem well. i read a reply of yours to another hobbyist and thought you might be able to help.

cheers... Aaron.

P.S. I know you guys in the U.S. dont use the metric system but i dont know the equivelant conversions; i think it's approximately a 75 Gallon (4 foot standard tank) and 22.5 pounds of added stones. Not sure if you needed that or not?

Answer
Hi Aaron,
I'm not sure exactly why the bubbles would have appeared after you added the stones. Maybe it was some kind of coating on the stones that is producing the extra bubbles? This really seems unlikely, especially after all the rinsing and pre-soaking you did. I wonder if it was a coincidence and maybe there is something else going on with the tank that just makes you think it could be the rocks. Testing your water wouldn't hurt, just the know the ammonia, nitrite and nitrate levels.
There are several causes to foamy water such as oily molecules, protein-like molecules, ammonia, etc.

The best solution to all of these potential problems would be several days of daily water changes. Some carbon added to your filter may be effective in removing whatever is coating the bubbles enough to make foam. Keep in mind that water conditioners can also cause foaming in your aquarium. Especially if the water conditioner was overdosed. Don't know if this is really what your problem is but it's just a educated guess I have.

One thing you could try is to see how the foam does when you turn off the undergravel filter. If they pop immediately, there is probably nothing wrong but if they stay in a steady foam that is definitely an indicator that something is in the water coating the bubbles and making their surface stronger. Again, water changes are the best solution to this until the foamy condition goes away.

Let me know if you get it straightened out!
Best of luck! (How's the weather in Australia?)
Karen~