Water changes with only cold tap water available

[Andrew_Thorichthysmeeki86]

Hello,

Does anyone know the ratio for mixing boiled water with cold tap water in a 5 gallon pail to refill an aquarium for 74°f or how I could figure it out? My house uses a water softener and the only taps that aren't on it are the ones that would have a garden hose attached to it. The closest one to the aquarium is in my garage. The temp out of the tap is around 45°f I think, or whatever is equivalent to 10°c. My kettle does 60oz.

[pedrofisk]

I think it'll take some experimenting. depending on how big a water change in total gallons you are doing you could run the hose to a large bucket inside then let the water come to room temp first. That may be close enough to do a small water change without dropping the temp in the aquarium too much.

[AdamTill]

Just get one of those $15 infrared temp guns, easy peasy.

I only have one 29 gal going right now, and I do weekly 50% changes.

I have a 20 gallon trash can, and I fill it with 15 gals from 3x5 gal buckets of cold.

I have a big steel cooking pot I keep for fish water and botanicals, and I fill that with cold and pop it on the stove. 

For all changes I’m aiming for 76F, but in summer I can get that with 90% of a boiling pot and in winter it takes the whole pot plus 2 kettles because the groundwater is so cold (still city water).

I mix in place, dechlor, and pump into the tank with an electric pump.

I use another pump and another line to drain.

All gets stored in the can when not in use.

Edited December 21, 2020 by AdamTill

[Coronal Mass Ejection Carl]

I deliberately avoid using hot water. Most water heaters are corroding away.

I fill a barrel with cold tap water where it's dechlorinated and heated with aquarium heaters.

[Maggie]

I heat a quart of water in the microwave to just under too hot to touch, and mix with approx 1.5-2 gallons of room temp water in a bucket, using my hand to measure against the tank water to ensure its the same. You'd be surprised how accurate it is. 

[FishyJames]

Physics was too long ago to remember how to calculate this.  I would just experiment with a five gallon bucket until you have it dialed in.  45 degree tap water is cold!!

[Colu]

I use a copper Atkins temperature probe very accurate

Edited January 23, 2021 by Colu

[Ken Burke]

the garage is about 45 degrees, what is the temp of the water.  I would fill the bucket the night before and let is sit in the house.  should be close enough for a 25% change.  

[ChemBob]

You can use the equation:

q = m * Cp * (Th - Tc)

Where 

 q is heat energy 

m is mass

Cp is specific heat capacity 

Th and Tc are the hot and cold temperatures 

The energy given ny the boiling water to the cold water should be equal, so

q1 = q2

Or

mc * Cp * (74F - Tc) = mh * Cp * (212F - 74F)

Or 

mc * (74F - Tc) = mh * 138F

Multiply through by the density of water and convert the mass to volume, so

Vh = Vc * (74F - Tc) / 138F

Where Vc and Vh are the volumes of your cold and boiling hot water and Tc is the temperature of your cold water in F. 

This takes some assumptions, but should get you within a couple of degrees. 

How this helps and wasn't too far Dien the science hole.