Need some help with my hydrofarm thermostat.

Hey everybody, I am using a hydrofarm thermostat with an exo terra UTH on a 28qt tub. I was wondering if anybody had a similar set up. I ask because I can't get my hot spot to 90 unless I set the thermostat to around 103, is this normal for a tub and this setup? Any input would be great, thanks a ton! :)

Track, I use a hydrofarm for a tank setup with an Ultratherm UTH and it stays within 3-4 degrees regardless. I also use one with my flexwatt under my tubs and it will go up or down depending on the temp of the room. I know it's not the same setup as yours but if I set the hydrofarm at 100, I get a hotspot of about 90 in a cold room. If I warm the room up I will have to adjust the hydrofarm lower because the hotspot gets to 97 or higher. Hope this helps.

Not familiar with the Hydrofarm but with my Herpstat or VE200 I do have to set it higher to achieve 90 or so in the tubs. I guess it depends on where you have the probe located as well. With me I usually set my thermostat to 93-96 to get 90. I also have a older Alife thermostat & usually had to set that around 100 to get 90 in the tubs.

Some people have suggested to use a dummy tub & set the probe in the tub then set it the thermostat to 90 to take the guess work out of it.

Where did you place the probe?

That will effect the answer to this it is not uncommon to have that kind of shift with the probe directly on the heat source especially if the room is cool (77 and lower)

The other issue with Hydrofarms is the accuracy of the temp they display is horrendous. I have a number I use a back up units and they all read incorrect temps. I have one that is 4ºF high the worst of the high end and one that is 3 low the worst of the low end. I'd not be worried about the temp it is reading it could be quite incorrect anyway.

IMO a reasonably accurate thermometer is important with this type of unit. Either invest in a good one (+/- 1ºF or better they usually run in the 200$ range and up) or buy 3-5 cheap ones and lay them all out together and use the ones that are reading the same or at least close.

I have the thermostat probe on the bottom of the tub taped to the outside of the UTH, (so, the UTH is sandwiched between the probe and the tub) I did this because if I taped the probe to the bottom of the tub, THEN put the UTH over it, it left a gap which was killing my heat. I have the thermostat set at 103 and it's holding a steady 89 in the tank.

I use a hydrofarm with no problems. However, I do plan to upgrade to a herpstat.

Anyway, my hydrofarm is set to 95 and I get a 88-91 hot spot in my tubs. I put my probe directly onto the flexwatt, but not under the tub. The tub tends to trap heat around the probe and make the temperature reading inaccurate.
My ambient air is around 70-75.

I also use a ranco on/off for a different rack. I have to set that one to 105 to get a 90 hot spot.

If your temps are fine and steady, then you're all good.

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That is fine as long as you feel the 89 is accurate. That is about what I'd expect if the room is coolish.

Depending on room temp, I've had to run as high as 107 degrees indicated, to achieve 90 ish degrees in the tub.

That's with with 3 inch heat tape. Right now, sitting unboxed in the back of my Blazer is a new rack from RBI with 4 inch heat tape. I'll be interested to see if there's as big a difference between indicated and measured with the wider tape.

The hydrofarm has a larger variance in degrees as it was meant for plants.

Its best to get a Temp Gun and spot check it till you dial it in. Also Room temp with the Hydrofarm will affect it quite a bit.

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Originally Posted by Slim

...Right now, sitting unboxed in the back of my Blazer is a new rack from RBI with 4 inch heat tape. I'll be interested to see if there's as big a difference between indicated and measured with the wider tape...

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Slim, that is high on my wishlist and I am hoping to get one real soon. Tell me how it is.