Boil or tankless water heater for changes?

JMurder

Obviously, I want the water I’m adding back to the tank after water changes to be close to or the same as the temperature of the aquarium water. The problem is I seem to have particularly cold tap water, especially this time of year. Is it ok to take the easy route of just adding a bit of hot tap water? Or do I need to take the safer and more labor intensive way of boiling water to add to the cold water. I have a tankless water heater so I don’t have to let it run for very long before the stagnate water is cleared from the system.
Thanks!
 

MacZ

I use RO, which usually is quite cold, for my waterchanges. I fill up a bucket and put a liter or so into an electric kettle, add a certain amount from the kettle to the bucket (admitted, eyeballing the amount because I have experience. Checking with a thermometer, though.), stir it and have the temp I want usually correct by 1°C.
 

BradleyH2O

I like to adjust my tap handle to where it’s close to the touch as the tank water, then I use a meat thermometer to fine tune it. Once I’m in the neighborhood, I start filling 5 gallon buckets and retest each buckets temp, before adding conditioner and dumping it in the tank.

The goal is to not have a major swing in temperature because I don’t want to shock the animals.
 

MacZ

The goal is to not have a major swing in temperature because I don’t want to shock the animals.
+/- 5°C is not going to shock the fish btw. Some may even be triggered to spawn that way.
 

JMurder

Now that I think about it, dechlorinaters remove heavy metals, so if the water picked any up in the heater it would be taken care of by the dechlorinater. Right?
 

Flyfisha

I am not going to argue with the logic of what MacZ has written. In fact I have tried triggering adult fish with cold rain water.
However JMurder you should go careful with your pet fish especially fry or very very young fry.

I am not going to guess what stresses fish but they all like stable.
 

MacZ

I am not going to argue with the logic of what MacZ has written. In fact I have tried triggering adult fish with cold rain water.
However JMurder you should go careful with your pet fish especially fry or very very young fry.

I am not going to guess what stresses fish but they all like stable.
There is nothing to argue. Not saying it's fine to be always that far off, but it's not putting the fish into shock if you do, let's say a 40% waterchange in a tank with 26°C water and add water of 22°C. Not like it's cooling the whole tank down immediately and to that lower temp. It will even out in the middle somewhere.
 

PAcanis

I'm in KG Tropicals camp. He did a video explaining his start in keeping multiple aquariums, a garage filled with them on shelves, and said he used to start WCs mixing in hot, but it did not take long to run out of hot and be using straight cold.
Never had a problem.

Here are some results I recently posted in another thread.
I started with 78F tank water (38g tank), replaced 25-30% with 59F RO water, and the temp dropped a whopping 3 degrees.

My Betta comes over and plays in the stream of cold water when I do changes in his tank. And so do the flame gourami and cherry barbs in another.

I've been doing 80% changes in my Platy fry tank every day and they seem none the worse.

If fish can survive water temp differences in the wild, I see no problem with a small change over time in our fish's tank. But you should do what you're comfortable with.
 

Thunder_o_b

For our RO/DI system we have three 30 gallon Brute trashcans linked to gather with heaters in the last two. Maybe something like that would help. I can post the build link if you like.

We are on water from a 100' well, so the water starts out very cold. Also have air stones in each can.
 

FishDin

I use the water from my hot water tap which, like yours, goes through an on demand (tankless) heater. My water heater is all copper. The water never contacts anything else. It's no different then going through copper pipes.

I also have cold water. In the winter it drops to the high 40-low 50sF. I just mix the hot and cold from the tap so that the temp from the tap is the desired tank temp. I hold a thermometer in the water stream from the tap until I get it right and then I'm good to go.
 

BradleyH2O

+/- 5°C is not going to shock the fish btw. Some may even be triggered to spawn that way.

If fish can survive water temp differences in the wild, I see no problem with a small change over time in our fish's tank. But you should do what you're comfortable with.
These are good points. If you think about lakes, ponds, or even the ocean, a fish can swim between different temperature zones caused by water stratification and be fine.

Not to derail the thread, but I always lumped tank temperature in with the acclimation process, so that’s why I try to keep the temp pretty close, but I guess pH swing is probably the real enemy when it comes to acclimation
 

PAcanis

Not to derail the thread, but I always lumped tank temperature in with the acclimation process,

Not to really derail the thread, but I always thought the acclimation process was akin to chefs saying to leaving a thick cut of meat out for a few hours to bring it to room temp. It takes a lot longer than a few hours to bring a 2lb piece of meat from 34F to 74F at room temp.

That said, I still acclimate 80% of the time. But I have my doubts whether or not floating the bag for 30 minutes really brings it up to tank temp. Of course that depends on shipping, heat packs and all the other variables.
If anything, pouring some of the tank water into the fish's container probably has a lot more to do with equalizing temperature.

But I follow blindly... most of the time ;)
 

Similar Aquarium Threads

Replies
17
Views
450
A201
Replies
9
Views
246
devsi
Replies
17
Views
201
LowConductivity
  • Question
Replies
18
Views
550
jmaldo
Replies
11
Views
6K
aquatic1

Random Great Thread!

Latest Aquarium Threads

Top Bottom