Ph v's TDS

[bluelagoon]

Re: Ph v's TDS

Through organic pollutants (DOC) left behind form food waste, plants, feces, fish respiration significantly lower PH or in this case also KH through ion exchange. This will alter the KH hardness of the water. I have very soft water here, so I either have to change water frequently or use coral in my filters to keep PH reasonably stable. I'd rather change the water. Sorry bout that. You're correct Willie the GH don't change much just the KH decreases.

[Willie]

Re: Ph v's TDS

Not to have an argument, Mervin. DOC are rapidly metabolized by the existing bacterial load, so the dissolved minerals would contribute to TDS. But at no time will TDS drop without changing water.

[brewmaster15]

Re: Ph v's TDS

My take...
The water in a biologically active aquarium is always moving towards acidic . This is due to co2 from respiration and from the effect of the nitrogen cycle. What keeps the pH stable is KH...carbonate hardness, which measures the amount of bicarbonate and carbonate ions in the water. When there are sufficient carbonates pH is stable...as carbonates decrease water loses its ability to stay at a certain pH and it starts to drift acidic.It will eventually reach a point where it can rapidly crash. Water changes can replace lost carbonates as can hobbyist added buffers.

This is pretty much your typical acid to base titration in chemistry...but its happening in our tanks.

[bluelagoon]

Re: Ph v's TDS

Yes, Willie fish food increases TDS and decreases PH. I don't see where I said that it didn't.