Quote:
Originally Posted by jords
This is in regards to I think the 1st reply on this thread (about pH buffers)...
IMO, I wouldn't use them...
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I would have to partially agree with ScubaSteve, it is clear there is a lack of understanding on the relationship between buffers, dKh, alkalinity and pH (no offence jords, it's just some well intentioned but perhaps ill advised advice). Carbonates, dKh, alkalinity and buffers ALL refer to the same thing with respect to marine aquariums, and they are essential to a healthy tank (FOWRL or reef). Stoney corals consume your buffer (carbonates) to combine them with calcium to produce calcium carbonate, the white stoney part of the coral left over after it dies. As your levels of carbonates in your tank falls, your tank loses it's ability to resist changes in pH. IME dKh values above ~6 degrees are sufficient to resist damaging shifts in pH, although keeping values above 8 will keep your corals much happier. In a FOWLR tank, water changes replenish the small amount of carbonates that are consumed, but less so in reef tanks. The only thing that has any significant effect on pulling pH away from it's natural resting point is CO2, either from the air, or respiration from metabolic processes in your tank. The natural resting point (I think this is referred to as pK), is controlled by the type of buffer you use. In marine tanks we are essentially restricted to a mix of carbonates and bicarbonates which will give a resting pH point in most tanks of ~8-8.3. If you are in a particularly polluted area with elevated CO2, you may be observing slightly lower resting pH, perhaps ranging from 7.8-8.1, than if your tank were elsewhere (ie ocean acidification). In this situation you could use a pH 'up' buffer, which contains borates. These have a higher pK (natural resting point for pH) and so will counteract the elevated ambient CO2 levels. I am just skimming the surface with respect to the relationship between buffers and pH, there is a lot more to it, but that should give you enough to hopefully make some informed decisions as to the use of buffers in your aquarium. Oh, and no need to buy buffers, just look up DIY dKh, it is essentially just arm and hammer baking soda but sold at 10x the price. I have been buying it from Costco in bulk for years and have 5 tanks of happy sps (~400G total).