RO Water and Its Benefits for Fresh water Fish setups? - If any

When I test TDS its usually at around 10.

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Can't speak for Cape Town specifically, as I'm a native Durbanite/current Joburger. But some municipal water suppliers bring the pH of the water supply up (often quite high) as water that is naturally too acidic can cause problems for water supply infrastructure (especially concrete: channels, holding, etc.). So they likely use a chemical additive to bring up pH, but in your instance one that does not contribute to the water's buffering capacity (hardness), like for example sodium hydroxide. So the water will pop out the tap at a very high pH, low hardnesses, but once exposed to biological processes in the fish tank (carbon dioxide, nitrogen cycle, acidic fish waste etc.) the pH should fall fairly easily.

 

Ah ok, thats interesting. Lately the PH has fluctuated quite a bit, TDS also.

Thanks

 

Our water in Centurion has been buffered quite high as well.
Out of the tap the pH measures 8.5, and it takes quite a few days before the pH falls even slightly.

 

I have read quite a few articles where the guys say that measuring the pH for fresh water is neither here nor their and mostly a waist of time for general setups, water hardness and nitrate and amonia levels are more important for testing.

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If this gives you a pH of 7.4 then I would trust that unless your indicator is really old. Chemical pH measurement is a first principle measurement - the only disadvantage is that the user has to interpret the data

 

They are not linked to each other. pH is a measurement of the -log[H+]. kH is a measurement of your carbonate hardness (carbonates and bicarbonate ions) while gH is a measurement of the general hardness (Ca2+ and Mg2+) ions. So the kH resists pH change as it buffers the water. If the kH is low the pH can be easily altered. The gH is how soft or hard your water is.

 

@TheGrissom , thanks for all the chemistry advice, I am determined to get my head around it and try to understand and make sense of water chemistry.

With regards to pH, I have read and seen videos where some fish keepers swear by a small bag of crushed coral, basically crushed sea shells, in their tanks to buffer the pH and keep pH levels stable. What are your thoughts on this?

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Been a hectic couple days and catching up on some of these threads

Personally, I keep sensitive fish but, dont believe in using RO water unless its like @TheGrissom and others have said, in very specific breeding situations

Firstly, probably 90% of the fish we buy today, have not been raised in all the fuss of RO water and their parents are also already most likely captive bred so we not looking at wild caught fish that have just been removed from their natural habitat
We looking at fish with generations of normal water

Even looking at fish like Discus, I know many people and we ourselves had a stunning Discus tank for a long time before going seriously into the rays that dont use RO water and they thrived
When you start looking at serious breeding.. I can understand but then again, many are breeding in normal water too

With RO water you obviously have to add all sorts of additives to ensure its healthy for the fish as they do need the minerals in the water as well so it becomes a constant nightmare of testing and worrying that your parameters and composition are steady
To me, the chances of a tank crashing and sensitive fish losses are higher due to the slightest mistake in re mineralizing the water, etc than them adjusting to your water and keeping it stable
Some crushed coral in the sump is ok if your PH really needs to be buffered but I wont fiddle with other things

Providing your basic parameters are good, most sensitive fish will survive and thrive on normal tap water
To me, stable parameters are more important than trying to mimic what we read up or the wild and like i said, the slightest mistake and you in trouble

I have a full SERA test kit.. we probably test water twice a year.... having to constantly check my water at every water change to make sure this is right and i added enough of that, would drive me nuts!!

But, this is just my 2 cents

 

Yeah, agree - I do do water changes via http://www.puresa.co.za/ but do not do any other additives when I do the WC or top-up straight form the tap to the filter to the tank ... keep it simple ..

Later Ferdie

 

No additives meaning no water conditioner either like seachem prime?

 

I ask cause I see the filter also removes chlorine, not sure about he chloramine

 

Correct ... - more than 10 years now ..

 

BTW not sure if everybody on this thread read https://www.tropicalaquarium.co.za/threads/ro-water-and-its-basics.6904/

Later Ferdie

 

Awesome, you've given me something new to think about...

 

So from past measurements - pH typically stays the same as does TDS via the filter ... it is not RO just a filter ;-)

Later Ferdie

 

Crushed coral/sea shells are basically calcium carbonate. At a high pH this stays insoluble in the water. If the pH drops then it dissolves into Ca2+ and (CO3)2-. Since pH is a measurement of the H+ ions in the water the (CO3)2- reacts with the H+ to produce H2CO3 which stops the pH dropping. When enough H+ has reacted the pH starts rising and when it reaches the level where the calcium carbonate stops dissolving the reaction stops. This is typically how a buffer works.

This only works if you want a mildly basic pH .

 

Thanks- I've not seen instances in general reading where tap supply has low KH but quite high PH so was wondering.

I use crushed coral in my community tank but found it took a while to really make much of an impact on my KH (tank in question's PH is 6.3). Coral useless as you say if the PH is above 7 as its insoluble.
Many people here in CT are unaware just how soft our water is and how important hardness is in general, to avoid PH swings.

I considered baking soda or Seachem alkaline & acid buffers to sort out the KH but with my W/C schedule I'm able to keep nitrates low enough that the low KH isn't an issue any longer.
Are neutral regulators bad news? I read they're not great for plants? One should not chase PH as they say but the idea of a magic wand that makes everything neutral sounds good on paper but never tried. My setups are stable now but I've been wondering given our tap supply here has been fluctuating a lot lately.

 

The above was back in 2012 ... maybe this is adding to the CT mystery?

Later Ferdie

 

Interesting. I however only discovered we had fluctuating PH in CT lately when I saw fish looking unhappy in my community tank after a 50% w/c - I’ve kept a consistent routine for the last couple years so it was odd given my nitrates are always low (when they are high the acidification rocks the PH boat).
Tested the tap PH randomly as it made no sense and discovered it had shot up to nearly 9 from the usual +- 7.6. I don’t use strips though - liquid based only. Called the water department and didn’t learn much. Will post the data they emailed me in a different thread - don’t want to derail this one into CT specifics but our water here is definitely very soft.
Go to some LFS (eg. Sam’s Aquarium) and you see pieces of coral in every tank. They use RO/ tap mix when I asked, as I’m sure most LFS here do, as needed for species.