will not hurt your parameters at all but greatly depends on the set up as a whole. My sand bed has been 1-1˝" running for the past 7ish years and my nitrates rarely if ever get above 5ppm.
If you wish to add more I wouldn't waste the money on LS
. It will become that way on it's own in a very short time. Just add some sugar sized oolitic or aquarium safe playsand on top. Adding a ˝" a day or so is best to allow the critters and bacteria in the sandbed to colonize the new sand without being deprived of necessary O2
. You will still most likley get a small diatom bloom but nothing to really concern you. Especially if the "crew" is already in place.
The last part of >>this
<< article should help..