Is distilled water free of chloramine?

Hmmmm....
Interesting questions. And yes - distilled water will have almost NOTHING in it, but little H's and O's (H2O). In fact, if made right, the stuff is basically not good for long term drinking use as it will strip out the electrolytes from your body. So yes, totally safe for aquarium use, if a tad bit expensive.
Ahhh, but then we come to dehumidifier water.
And to that I say, "Be Careful".
Why?
It's the air in your home. That water collected by the dehumidifier has basically been condensed from the humidity (water vapor) found in the air of your home. And therein, as they say - lies the problem.
Homes are made of all sort of things that can ultimately get up into the air you breathe in them. Cleaning chemicals. Non-stick pot and pan coatings. Paint and paint primers on your walls and trim, (that may still be off-gassing all sorts of things). The fungus/mildew retardant sealant used on your windows and doors.... the list goes on and on.
Full Disclosure: Yes, I water some more sensitive house plants with the water collected and saved from my home dehumidifier. But, I DO NOT trust that stuff as top off water for my aquariums! That sort of specialty (RO) water is purchased at the LFS for $0.25 cents per gallon. In actual use, I typically burn through about 6 to 8 gallons of that purchased RO water every two weeks.

As said above DI water contains nothing, and because it contains nothing (as in any vacuum, it desires/needs to be something) it wants stuff.
That's why if you drink too much DI water, it has the ability to leach calcium, and other minerals from your system, (your bones and organs)etc.
It can also has the same osmotic effect on fish, if "too" much is used without remineralization.
Used sparingly a small amount as top of water needs no alteration.
Salt water keepers use DI to as top off water all the time, so as not to alter salinity and mineral content.

So for cichlid keepers (if you are going to use a lot), this is where re-mineralization comes in, and where at times pH alteration may be needed.
With cichlids (and other freshwater fish) remineralization depends on the species you keep, and the habitat they come from.

If you keep S American soft water species , often little mineralization isn't needed, because their water is devoid of some minerals (but not all, so it is cut with a littletap water)


The chart above shows selected waters in the Amazon basin of S America,
However
If you keep African rift lake species, or Central American species, the water there is quite different, and mineral rich
In this case, remineralization with African rift lake salts, may be needed, (again if you use a large amount of DI), to keep the osmotic conditions right for the water they have evolved to live in. Below Central American water and rift lake water are very similar.

I must admit, even though I am a retired chemist, I find that kind of water parameter chasing to be too much bother, and simply keep the type fish, that have evolved to live in my tap water.
So I don't fool around with using DI, or any pH alteration.
Using a dechlorinator, (my intention) is to do enough water large changes to keep nitrate below 5ppm.
This is enough for me.
For my Panamanian species a pH of 8.2, and lots of natural minerals, is perfect
I collect all my fish from nature in Panama, and test water parameters in whatever natural water I collect in.

The 2 most dominent water parameters I find all waters I've tested so far here in Panama, have been pH values in the 8s, and undetectable nitrates.

Ok.

A chloramine follow up question:

I have several 'hang on the back' filters with sponges that require regular cleaning, with each cleaning requiring a bucket of water and repeated sponge squeezings and bucket refills. I have plenty of sponge filters so I just clean the ones I take out in tap water (that contains chloramine) and set them aside to dry while putting in a fresh set of well-dried set sponges in the filter from my stash of sponges. (I have quite a stash of sponges)

Question: I have been assuming that once a sponge has thoroughly dried and been set aside for a couple weeks that there is no chloramine of any fish consequence remaining in that sponge.

Am I correct? Or not?

(I am not worried about losing any colonies of bacteria in these sponges, or having bacteria in the sponges I replace them with. I am confident that my tanks and the filter housings themselves are loaded with bacteria that will quickly colonize any filter media I put in there. I am very confident of this.)

Another way to clean sponges (the way I do it anyway) to avoid chloramine, or chlorine contamination.
Is remove some aged (yet clear) water from the tank during a water change and squeeze the sponges out in it.
In this way you accomplish two tasks simultaneously.....adding new volume to the wanter change, and cleaning the sponge.
(I also use the gunk filled water on house plants, to add a little extra natural fertilization)
This helps to help retain the beneficial bacterial population in the sponge, and not exposure it to any of the disinfection water chemicals, the sponge is then put it back in the aquarium, free of most gunk, but also still wet, and still bio-actively charged with healthy bacteria.
I do not let the sponge dry out, causing the beneficial bacteria to go inert, so they can still continue to do their job.

There is a theory that by cleaning the sponges in this way, many of the robust bacteria are left behind, and only the less viable biofilm goes down the drain, or on your house plants.

- Squeezing out the sponges in a bucket of tank water during the water change sounds like the ticket (that's when I clean the glass, just one more maintenance step to perform while I'm watching water go in or out).

- Yes, it wouldn't hurt to add a little Prime to the distilled water, to be safe.

I actually haven't been using much distilled water. My lids are good and I do weekly 40% or so water changes, so, so far at least, I'm not seeing a hardness creep from tap standard. But, I suppose some kind of schedule will eventually emerge for the addition of distilled water to keep hardness creep at bay. Or I could occasionally double down on the water change and do a couple near back to backs. I don't think any of my tanks have deviated much from tap parameters. At least, not in any way I can measure.

I probably should pump the tank water out to a water barrel for the garden rather than down the drain. I recall a Science Fair project one of my kids did. He mixed up some sand and peat and then filled three one-gallon pots with the mix and transplanted a tomato seedling (from the same seed stock) into each pot. One pot received tap water only, one pot received tap water augmented with some liquid fertilizer, and the third pot received water from a fish tank I had set up at the time (a 180 heavily-stocked African tank). The tap water only tomato was relatively puny compared to the others and the new growth ten weeks down the line was a tad pale, but those Africans did their job. The fish tank tomato was neck and neck with the Miracle Grow in both size and color! (early vegetative growth is heavily reliant on N, P and K shine later)

I learned early on that distilled water at water changes, as stated above, strips the tank of needed minerals in the water column. I used it regurlarly at WCs fpr several months and it cost me many fish. The tanks were only 20g, so $5-$10 a waterchange was affordable. But a hard lesson learned. Then, about 6 years ago, I considered an RO system. However, that is essentially the same as using didtilled water. It requires remineralization. So, I installed a water purification system.. It is between my water source and my large office tank. I diligently studied to get the best system, so I no longer needed to use any water conditioners. So I thought ?! It did remove all chlorine and chloramine and sediments. But after another bout of fish loss, I discovered it didnt remove heavy metals. Those were harsh to my fish, left in water. *** been using my tap water since then, with a slightly exaggerated amount of Novaqua Plus, by Kordon It removes everything I want gone and leaves everything I want still in. I will never express to know everything, however I will certainly share my journey, if it can help anyone else.