Low PH and KH cycle

[mbsqw1d]

I'm helping someone out who's setting up 64l for a Betta. Its planted. Their KH is 2 and their PH is 6 at the most. They used API quickstart to feed the tank with bacteria, but it looks like their cycle crashed the other day, I assume the KH depleted and the PH swung too low.

I understand that ammonia exists as harmless ammonium in low PH setups, therefore, is there a need to attempt cycling at all?

When they perform a water change, they'll essentially be removing ammonium, but the danger is that if for some reason their tap water is 7+ PH, any ammonium will become ammonia and potentially kill the Betta? Basically replicating the 'old tank syndrome' scenario.

Does anyone keep low PH tanks and can advise how they keep it maintained?

Ive advised them to get LOTS of plants, more than they already have, as I wouldve thought that ONE Betta in a 64l tank isnt going to produce that much ammonia/ammonium... and the plants would likely take care of that?
Thanks.

 

[eatyourpeas]

I am using Seachem Alkaline Buffer to correct KH and it slightly increases pH. I deal with inconsistencies from the water supply so am always carefully monitoring and correcting.

 

[Essjay]

If the tank is planted there shouldn't be a problem as the plants should remove all the ammonia.
We have members with virtually zero GH and KH (eg Byron, who has been keeping a lot of fish successfully for decades), and those who use pure RO water (eg seangee) - they don't add any buffer and their fish are fine.
Do you know the pH of their tap water - both freshly run and a sample that's been allowed to stand overnight?

As you say, one betta in 64 litres won't make very much ammonia. Plants should take care of that amount easily, especially floating plants. I quarantined 12 kuhli loaches in a 25 litre tank with no mature media, just 2 large water sprite and 2 bunches of elodea. That's a much bigger bioload than one betta in 64 litres

 

[seangee]

Plants and regular substantial water changes. As @essjay says the betta will be fine. The danger is when the KH is depleted the pH keeps dropping. This is fine unless you need to do an emergency water change for any reason and your tank pH is considerably lower than your tap.