Heaters can complicate a startup because of rapidly raising the LSI
In the Orenda Startup™, do not turn on a pool heater until day 5, and only if there is no plaster dust in the pool. If you are doing our startup process, plaster dust should not be an issue in the first place, and certainly not after five days of treatment.
Our primary concern with heaters being turned on too early in a startup is the rapid change in the LSI of the water. The Orenda Startup™ is based on the LSI before all else. Quickly cranking up the water temperature causes a sudden change in LSI that could lead to scaling the pool. And sure, a high-LSI violation like this will not damage the pool, per se, but it can discolor plaster, and cause problems.
It is our recommendation to gradually heat the water over several days. Do not raise the temperature by more than 15º per day. So if your tap water is 50ºF, on day 5 you can raise up to 65º. Day 6 could be up to 80ºF. This slower rise in temperature gives your water more time to equalize and adjust. It also gives SC-1000 more time to keep metals and minerals in solution (if it has not already bound to all the calcium by day 5 for some reason).
No plaster dust
The NPC Startup guide does not give a timeline for when to turn on the pool heater, but does say that it should not be turned on until there is no plaster dust in the pool. In our case, you should not have plaster dust anyway. We still like to wait those five days to give your cement the chance to cure as evenly as it can in stable conditions before changing the temperature.
For more information about the Orenda Startup™, try the links below: