dreaming reef gravel??

[asylumdown]

it's entirely possible that this gravel is leaching phosphate.

If you want to test it, take some if your gravel, put it in a sealed 5 gallon bucket, and fill the bucket with R/O water and put it somewhere dark. Test the water immediately after filling, then again every couple of days for a week.

I've also heard you'll get a more 'true' reading of the phosphate that's actually in the water if you heat it up to 80 degrees C before you test it. Supposedly it causes some of the bound phosphate that might be available to plants but invisible to the test kits to decompose, though plant available phosphorous is a surprisingly more complex and difficult to account for parameter than you probably would think (seriosuly, google the Hedley Fractionation Method to get a sense of just how far scientists have to go to measure plant available phosphorous).