Is it safe to use rainwater to lower tank pH?

[Tacocat]

Here in my city, we have "Toronto is considered moderately hard at 6 to 7 grains per gallon" and "Falls into the "moderately hard to hard” category" which I find quite vague. The water company isn't very helpful either, as the water is run by the city and i can't find water hardness on the website.
Upon testing my pH, I find that my water is about 7.8. This is a bit high for my fish(Betta and tetra and rasboras), and I have posted a few other threads on the subject. However, I just had an idea about using rainwater to lower the tank pH, as because the rainwater here in the city is likely acidic, it might be able to lower the tank pH. However, because it's falling from the sky through layers of smog and pollutants, I'm wondering whether it's safe to use or it's better not to. I feel that the answer is quite obviously absolutely not but I just want to ask experts.

 

[Colin_T]

Rain water that is acidic usually has pollutants in it. If you live in an area with lots of smog from industrial air pollution, then the rain water is probably not suitable for fish.

If you live in a reasonably clean area and the pH of the rain water is 7.0, then it should be fine to use.

If you are concerned about pollutants, don't start collecting rain water for the first 15-30 minutes of it starting to rain. This allows the first lot of rain to wash the dust out of the air and off the roof and gutters, and gives you cleaner water.

Pure rain water has 0GH and a pH of 7.0, It might lower your GH and pH a bit if you mix it 50/50 with tap water. You can also filter the rain water through peat moss to lower the pH. However, this usually causes the water to turn yellow or brown from the tannins in the peat. The tannins are harmless but do make it harder to see the fish.

 

[Kimbereally]

Nooo absolutely not. Rainwater is really dirty and has bacteria and who knows what else in the atmosphere. You can always just buy a neutral regulator- which usually u can just add right into the tank. I personally use the Seachem brand one- they have different ones but the one I have regulates the pH and brings it down to 7.0. There's plenty of other brands out there too but Seachem is pretty great. U should never put rain water or even straight sink water without treating it first, which a good dechlorinator and regulator can do a good job of and fix your problem.

Here in my city, we have "Toronto is considered moderately hard at 6 to 7 grains per gallon" and "Falls into the "moderately hard to hard” category" which I find quite vague. The water company isn't very helpful either, as the water is run by the city and i can't find water hardness on the website.
Upon testing my pH, I find that my water is about 7.8. This is a bit high for my fish(Betta and tetra and rasboras), and I have posted a few other threads on the subject. However, I just had an idea about using rainwater to lower the tank pH, as because the rainwater here in the city is likely acidic, it might be able to lower the tank pH. However, because it's falling from the sky through layers of smog and pollutants, I'm wondering whether it's safe to use or it's better not to. I feel that the answer is quite obviously absolutely not but I just want to ask experts.

E e

 

[itiwhetu]

Gosh it is moments like this I love the West Coast of New Zealand. All our water is rainwater coming off the roof of our house, we have a simple filter on the pump. But we wash in it drink it you name it. We have been here for five years it is the best tasting water ever.

 

[xxBarneyxx]

I think this is one of them questions that you will get a different answer to from every person you ask, and even the conflicting answers may still be correct depending on where people live and how they do things.

I've known people that use rainwater mixed with tap water with no issues. Personally though I feel there is often too many opportunities for pollutants to get in the water and no way to know for sure how safe it is to risk it.

That being said I have happily collected and drunk rainwater for myself when camping. Not sure I would do the same for water collected off a roof in a densely populated area though.

 

[Essjay]

6 to 7 grains per gallon" and "Falls into the "moderately hard to hard” category"

Grains per gallon is virtually the same as dH. 6 to 7 grains per gallon = 5.8 to 6.7 dH. This is the upper end of soft not moderately hard. Water provider words often make it sound harder than it really is which is why we ask for numbers.

If you want to use rainwater, it must be collected:
in an area with no industrial pollution
in an area where farmers do not spray crops
the roof is not made of something that will contaminate the water
there is nothing laying on top of the roof which will contaminate the water (eg the seagull poop on our roof)


If the roof material is safe and there's no industry/crop spraying, and you can guarantee you'll have some available all year round, rainwater is OK to use.

 

[FishHobby99]

is it possible to filter out contaminates in something like a Britta Filter?

 

[xxBarneyxx]

is it possible to filter out contaminates in something like a Britta Filter?

Short answer, no. Only way to be sure would be to use an ro unit. But then you don't need rainwater.

 

[FishHobby99]

Thanks, I like short answers!

 

[Byron]

@Tacocat to your question concerning rainwater, others have answered. But there may be a misunderstanding on the pH issue.

First, you do not ever attempt to raise or lower the pH on its own. Sometimes this may be successful, but most of the time it will fail. The reason is, the pH is connected to the GH and KH. IF these need adjusting, it is the GH and/or KH that is targeted, and the pH will tag along as it were. Of course, other factors like CO2 can be relevant too, another reason to leave parameters alone.

The GH of your water seems to be as @Essjay worked out. I would leave this alone because a betta will be fine. The pH may stay where it is or it may lower over time as the organics accumulate in the tank. But whichever is fine for a betta. And most soft water fish species too for that matter.

 

[Naughts]

If you stick with tapwater, your betta will appreciate the regular addition of an Indian Almond leaf.

 

[FishHobby99]

I’ve seen those leaves. What’s the benefits other than looking cool?
I use conditioned tap water.

 

[Byron]

I’ve seen those leaves. What’s the benefits other than looking cool?
I use conditioned tap water.

All dried leaves including these (others like oak, mapel, beech are good) slowly decompose. As they do, they release tannins, and there are some bacterial benefits (nothing to do with nitrifying bacteria). Like all organics, they can lower the GH and pH, subject of course to the initial parameters "buffering" capability, and other factors that might work against this, as for example calcareous rock/substrate, shells, coral, etc.

EDIT. Naughts caught a few things I missed, I agree.

 

[Naughts]

I’ve seen those leaves. What’s the benefits other than looking cool?
I use conditioned tap water.

Apparently Indian almond leaves lower pH levels and have antifungal and antibacterial properties. They are a good source of infusoria. They provide tannins which make the fish feel safer and reduces stress - it is more natural, as well as darker so they feel less exposed to predators. Our betta definitely has healthier fins when we use them.