When my controller suddenly stopped working the day I had planned to start my second round of seeds, I frantically searched for a replacement from local stores: none available. I had to get a Vivosun ( with a set point max over 100 degrees) from Amazon.

On day 2 of my second round of seeds, I realized the new controller wasn't able to maintain the set point (86 degrees): it erratically ranged 4 degrees lower to almost 1 degree higher.

I will be returning it and getting a replacement for this bad replacement.

But where to find one?? And what brand is accurate and reliable?

Hello Bet,

" I had to get a Vivosun ( with a set point max over 100 degrees) from Amazon. "

You didn't "have to get" that particular controller model from Amazon. Amazon has literally pages of choices, with reviews that award many stars for most of them.

https://www.amazon.com/s?k=see...

" On day 2 of my second round of seeds, I realized the new controller wasn't able to maintain the set point (86 degrees): it erratically ranged 4 degrees lower to almost 1 degree higher.
I will be returning it and getting a replacement for this bad replacement. "

Actually that doesn't seem like horrible performance to me. It should be able to germinate seeds. But let's wait and see how well that replacement works. The controller can't work miracles. It is totally limited by the capability of the heating mat. And by where you locate its temperature sensor.

You should be able to get a workable controller on Amazon. I don't know of a better source.

ZM (not associated with any product or vendor mentioned or linked)