Substrate for UNDER tile?

[morphmom]

-My current set-up in sand under my ceramic tiles. This has been working really well, BUT crushed walnut is cheap and useful for my crafts.
-Could I put crushed Walnut shell under my tiles? I really want a buffer because my tiles fit very tightly together and I'm afraid of banging the tile on the bottom of my tank and breaking it
-Would crushed walnut be a fire hazard? I'm asking because the heat would have to be hot enough to penetrate the walnut and the tile.
-Am I worrying too much!? LOL! Cause I do that a lot!

(I tried searching for this answer and couldn't find any info on crushed walnut for under tile.)

Any help would be VERY appreciated!

 

[Phantom240]

I don't know if I would recommend walnut shell, because the coarse nature means there's a lot of air trapped in it, meaning it's going to insulate your heat source from your tiles. If you could find something finer that conducts heat better, like fine sand, I think that would work better. Just my opinion. I'm not an expert by any stretch of the imagination.

 

[DrCarrotTail]

If you put something under your tile you want it to be a heat conductor. Sand works well and probably increases the efficiency of the heat transfer (if its needed). The crushed walnut shells would probably act more as an insulator and prevent heat from traveling across them to the tile.

Basically exactly what Phantom said....haha

 

[Lavodnas]

I agree with both comments above. If you're looking for a better sand price wise, you could always go with play sand. Not that you would need as much as I did (125 gallon fish tank project), but I bought a 50 pound bag at a hardware store for about $4.00.

 

[wombat2000]

Just as a follow-up question, is a substrate underneath the tiles absolutely necessary? I just installed slate tiles in my 20L and didn't put any substrate underneath the tiles, so the tile is directly on the glass bottom. The tile surface temp still gets to 90+ just fine, but I'm wondering if I still need to add sand beneath the tiles.

 

[morphmom]

Thank you all very much for your replies. It all makes very good sense. Guess I'll keep my walnut for just my crafts
-In regards to your question wombat2000, I have read that you do not need any substrate under your tiles. I'm just very prone to dropping things and I can see myself banging a tile off of my viv bottom. *sigh* I will say that I've never had an issue with maintaining proper temps with having the sand. I even have my UTH on a lamp dimmer, tho it is only "dimmed" very, slightly I also use a textured ceramic tile and find that works very nicely, at least, for me.

 

[Phantom240]

I guess it really depends on the bottom surface of your tiles. My slate isn't perfectly smooth underneath.

 

[DrCarrotTail]

I would think it depends on your tile and your UTH so whether or not you need anything in between would be kind of a case by case basis. If the heater is barely making the glass hot enough it probably needs a very good conductor between the slate and glass (or you need a new heater). If it is seriously hot you could put nothing over a 1/4 inch gap and it would work fine. If it's just right you may be able to go either way. Whatever you do, the important thing is that your gecko has a 90 degree warm spot no matter what you're using