ph crash

[ryannxs]

hi guys i have a bit of an issue, ive recently started using ro and now my ph has dropped to below 6. the water is coming out of the ro at about 6.6-6.8 any ideas?

 

[pauldoit]

RO water will have a pH around 6 due to dissolved CO2 from the atmosphere giving rise to carbonic acid in the water. Water lacking in buffers ( like RO water) can suffer large pH changes. When using RO water for discus a while ago I put in a coral bones, say a handful in a 6ft, to stop pH crashes. Trial and error on the amount to get the desired pH stability. measure pH and KH and GH and look for tables on the net for the relationships. carbonate buffers can also supply CO2 for plants if you adjust the pH down. Hth.

 

[Lornek8]

RO water is pure, so much so that there is no buffering capacity to the water so any slight additions to the water can cause a major swing in the parameters. Ph is an average of acidic and alkaline components in the water. If you have one unit of 6.0 acidic components and one unit of 8.0 alkaline components you'll have water of ph 7.0. If you add just one more unit of either the acid or the base you'll see the ph swing dramatically. If you have 100 units of each the basic and alkaline components and add just one additional unit, the overall effect will be slight in comparison. That's the difference between RO and water with more mineral buffers.