Pull unused analog pins to gnd to help minimize noise?

@Gordon

As you're not expecting that to change much, you could just keep some
kind of running average of it:

Right, I will expect the temperature of my aquaponics fish tank to be: 72-74 degrees F.

What I am afraid of is, turning the water heater on or off when its not supposed to due to the fluctuations and then in-turn causing the heater to break :-/

I'm getting values between 104F - 110F(Hot water demo)

The values that I am getting(using hot water as a demo):

Temp in F: 105.52142546252
Temp in C: 41.34653038471

Temp in F: 106.42375469248

Temp in C: 41.30234757616
Temp in F: 106.34422563710

Temp in C: 41.51487649546
Temp in F: 106.72677769184

Temp in C: 41.55840707979
Temp in F: 106.80513274363

Temp in C: 41.22329070578
Temp in F: 106.20192327040

Temp in C: 40.82283922169
Temp in F: 105.48111059904

Temp in C: 42.56068147354
Temp in F: 108.60922665237

Temp in C: 41.90883827124
Temp in F: 107.43590888824

Temp in C: 42.11013715285
Temp in F: 107.79824687513

Temp in C: 41.61748517983
Temp in F: 106.91147332370

Temp in C: 41.74432203951
Temp in F: 107.13977967112

Temp in C: 41.35120766480
Temp in F: 106.43217379665

Temp in C: 41.92938665155
Temp in F: 107.47289597280

Temp in C: 41.80511869209
Temp in F: 107.24921364577

Temp in C: 41.53246010569
Temp in F: 106.75842819024

Temp in C: 43.58086790083
Temp in F: 110.44556222151

Temp in C: 41.64385517750
Temp in F: 106.95893931950

Temp in C: 41.74612988558
Temp in F: 107.14303379405

Temp in C: 41.99619187463
Temp in F: 107.59314537434

Temp in C: 41.66354537383
Temp in F: 106.99438167290

Temp in C: 40.64783023314
Temp in F: 105.16609441966

Temp in C: 41.62779064556
Temp in F: 106.93002316202

Temp in C: 41.50174732836
Temp in F: 106.70314519106

Temp in C: 40.55533498825
Temp in F: 104.99960297885

Temp in C: 41.71990880225
Temp in F: 107.09583584405

Temp in C: 43.50436386718
Temp in F: 110.30785496093

Temp in C: 41.60630366626
Temp in F: 106.89134659928

Temp in C: 41.74936786270
Temp in F: 107.14886215287

Temp in C: 41.39160510339
Temp in F: 106.50488918610