I'm not following you. Dosing a carbon source dosing is not related to carbonate hardness except for the fact that high alk levels will cause burnt tips and tissue recession. With the burnt tip phenomenon, the amount of the carbon source being dosed to get to a low nutrient level doesn't matter, the alk level is the value of concern. Your comment seems to indicate that dosing a carbon source will increase carbonate levels - not true at all. A carbon source (vodka, vinegar, sugar, vit c, etc...) is not in any way the same as carbonate which is used for building skeletal structure. Coral health and increased growth can easily be maintained at and above 12dkh (when carbon source dosing isn't being implemented). In fact, quite a while back Tatu had sent me an article that showed SPS growth rates continued to increase as alk levels were increased all the way up to 24 and 25 dkh. When dosing a carbon source to bring nutrients to a low level it's often observed that many SPS will exhibit burnt tips (tissue recession and browning of the tips) as well as tissue recession in other areas if the alk level is above 8 dkh. When the alk level is maintained between 7-8 dkh these negative reactions don't occur. It has absolutely nothing to do with a carbon source overdose. Here is a quote from the article I posted:
My question is have the corals exhibited the same reaction of burnt tips with alk levels above 8dkh when the carbon source is the biopellets. Again, that's why I'm asking those whom are using the biopellets what their alk levels are maintained at.
Jeremy