Ways to lower ph with water?

blackwater
  • #1
So I have a 15 gallon fluval with a ph of 7.6, a bit on the higher scale. I usually do water changes with a 5 to 3 ratio of tap to ro water. My ro water's ph is 6.8 and my tap is around 8.0. Would it be possible to lower the ph with just 50 percent water changes every week with ro water? if not, any other suggestions are appreciated ( I can't convince my parents that botanicals aren't just expensive decor, and I can't really forage for any outdoors.)
 
ProudPapa
  • #2
Are you absolutely sure you need to lower it in the first place? I have a wide variety of fish and invertebrates doing just fine in 8.2 pH water.
 
MacZ
  • #3
Are you absolutely sure you need to lower it in the first place? I have a wide variety of fish and invertebrates doing just fine in 8.2 pH water.
That is indeed the first thing to check.
Do you keep any softwater fish? (South American, Central/West African, South East Asian)
If yes and you have the option to use RO, allright. Let's go on.
If no: Don't bother. Hardwater fish won't mind your water parameters.

Next:
My ro water's ph is 6.8 and my tap is around 8.0.
Which is irrelevant.
The KH determines pH. RO has no KH. So in RO the CO2 from the air determines the pH. Your tap most likely has KH, so it has a higher pH. And pH, CO2 and KH balance each other out. That also means the pH of your RO may well be not what you measure. It takes at least 2° KH for pH driptests to be reliable.
When you cut water with RO, you cut down on KH and GH. One part tap, three equal parts RO and you end up with 1/4 of the original values.

Also don't aim for a pH number between 7 and 8. Either leave it alkaline and hard if it suits the fish or go full acidic softwater (100% RO, pH around or below 6). But don't try anything inbetween, it will only be unstable.
 
blackwater
  • Thread Starter
  • #4
That is indeed the first thing to check.
Do you keep any softwater fish? (South American, Central/West African, South East Asian)
If yes and you have the option to use RO, allright. Let's go on.
If no: Don't bother. Hardwater fish won't mind your water parameters.

Next:

Which is irrelevant.
The KH determines pH. RO has no KH. So in RO the CO2 from the air determines the pH. Your tap most likely has KH, so it has a higher pH. And pH, CO2 and KH balance each other out. That also means the pH of your RO may well be not what you measure. It takes at least 2° KH for pH driptests to be reliable.
When you cut water with RO, you cut down on KH and GH. One part tap, three equal parts RO and you end up with 1/4 of the original values.

Also don't aim for a pH number between 7 and 8. Either leave it alkaline and hard if it suits the fish or go full acidic softwater (100% RO, pH around or below 6). But don't try anything inbetween, it will only be unstable.
I'm planning on keeping some apistos and pygmy cories, which require relatively low ph to my knowledge. Tank is cycled and just waiting for the vals and dwarf sag to grow in.
 
MacZ
  • #5
some apistos
Which species? Wild caught, wild form or domestic?
which require relatively low ph to my knowledge.
Rather low conductivity. And at least for the Apistogramma depending on the species.
 
blackwater
  • Thread Starter
  • #6
An apisto borellii pair which my lfs says is captive bred
 
MacZ
  • #7
Then you can leave everything as is. In the wild they are a wide spread species and live in a wide range of parameters. You can for sure go softer, but you don't have to go more acidic. Technically for both species Apistos and Corydoras GH 0, KH 0, pH 5-6 and EC of 50µS/cm would be close to the average parameters in nature and they would profit from it. But they don't require it necessarily.

The question is: How much are you willing to recreate their habitat? With RO you have the means to go all in. You better decide that before getting the fish. Because there is no turning back in a week, you will have to stick to it at least for some months for the tank to adapt.
 
blackwater
  • Thread Starter
  • #8
I think that I will stick to the gradual lowering of the ph. It'll help the tank become more established anyhow. Thank you for your advice MacZ
 
coralbandit
  • #9
blackwater
  • Thread Starter
  • #10
BlockHead1981
  • #11
Your pH is fine, your fish should adapt. What they won't do well with are pH swings. Unless you're trying to breed or your pH is way high like 9 then I wouldn't mess with the pH. But to answer your question, you can use pH down, Indian almond leaves.
 
Itiwhetu
  • #12
Aquarists should always aim to have an acidic tank; the main advantage is that you reduce the chance of an Ammonia spike. Besides that, most of the species of fish we keep in aquariums prefer soft/ acid water.
 
MacZ
  • #13
Your pH is fine, your fish should adapt. What they won't do well with are pH swings. Unless you're trying to breed or your pH is way high like 9 then I wouldn't mess with the pH. But to answer your question, you can use pH down, Indian almond leaves.
And this is why I said: Leave things as they are or go full softwater.

And pH-down should be prohibited. The way it works it defies everything one wants to reach with a softwater tank. It's not about the pH, it's about TDS and conductivity when you do that. RO, distilled and rainwater all are water types with little to no dissolved things in them. Pure water with very low conductivity. pH-Down products are diluted acids that add not only acidity but also ions, thus raising conductivity.
IALs alone do nothing in water with measurable KH, only in very soft water they have lasting effect.

Dangerous pH-swings in soft water are a myth. Planted aquariums show nightly differences due to photosynthesis pausing and plants releasing CO2 anyway and high-tech planted tanks are worse in this than softwater tanks.
With pH-changes in general, it's always how amplitude and time work together. High amplitude (> 1), short time-frame (<1 hour) = dangerous. Usually either the amplitude is negligible (< 0.5) or the timeframe (>1-2 hours) what people observe and panic about needlessly.
And pH-crashes are out of the question as long as nitrates are low and significant amounts of humic substances are present.

Ammonia (NH3) spikes can still happen in acidic water, but below a certain pH ammonia is all present as ammonium (NH4) which is barely toxic in comparison.
 
BlockHead1981
  • #14
And this is why I said: Leave things as they are or go full softwater.

And pH-down should be prohibited. The way it works it defies everything one wants to reach with a softwater tank. It's not about the pH, it's about TDS and conductivity when you do that. RO, distilled and rainwater all are water types with little to no dissolved things in them. Pure water with very low conductivity. pH-Down products are diluted acids that add not only acidity but also ions, thus raising conductivity.
IALs alone do nothing in water with measurable KH, only in very soft water they have lasting effect.

Dangerous pH-swings in soft water are a myth. Planted aquariums show nightly differences due to photosynthesis pausing and plants releasing CO2 anyway and high-tech planted tanks are worse in this than softwater tanks.
With pH-changes in general, it's always how amplitude and time work together. High amplitude (> 1), short time-frame (<1 hour) = dangerous. Usually either the amplitude is negligible (< 0.5) or the timeframe (>1-2 hours) what people observe and panic about needlessly.
And pH-crashes are out of the question as long as nitrates are low and significant amounts of humic substances are present.

Ammonia (NH3) spikes can still happen in acidic water, but below a certain pH ammonia is all present as ammonium (NH4) which is barely toxic in comparison.
Interesting. My friend has a fish tank and he uses pH down after every water change. His pH is in the mid 9s and he lost half his fish once when he forgot to dose. I'm no expert but in his particular case, it allows him to use his tap water which is much more convenient than RO water. Not sure how it actually works but it does, his pH stays around 7.
 
MacZ
  • #15
Interesting. My friend has a fish tank and he uses pH down after every water change. His pH is in the mid 9s and he lost half his fish once when he forgot to dose. I'm no expert but in his particular case, it allows him to use his tap water which is much more convenient than RO water. Not sure how it actually works but it does, his pH stays around 7.
Convenient to chugg acid in the tank each week, yes. Sustainable? Rather not. Getting an RO unit would pay off quickly, actually.
Also, is it safe? Neither. The fact forgetting it killed his fish makes this risky business. You can forget to dose it, you can underdose, you can overdose. It drives up the water's conductivity to heights that are also unhealthy to the fish that way.

Fixes from a bottle come at a price not on the tag.
 
blackwater
  • Thread Starter
  • #16
I think I will slowly convert to soft water using my ro water. Thank you for all of the info!
 

Similar Aquarium Threads

Replies
43
Views
3K
kered
Top Bottom