Anyone out there still use Onyx Sand? I am setting up a 40 gallon with Onyx sand used over mineralized soil. I will be injecting co2, and the water here in NYC is acidic(I think it comes out of the tap at 6.8.) I guess I am worried that the buffering ability of Onyx will make setting the correct target co2 a pain. Should I be worried?
So I went ahead and set up the 40 gallon last week with the Onyx sand. The water here come out of the tap at around ~1.5 kH, and I am getting 5kH from the aquarium right now(I just changed 50% of the water or Sunday.) It may make it hard to keep a target and steady co2 concentration as the kH will always be drifting up.
I am having a hard time reading the API ph test kit it could be 6.6-6.8. I suppose if I do a weekly 50% water change, it won't be too much of a problem. What do you guys think? Should I think about changing to another substrate, or wait to see how the plants do after several weeks?
So it seems the Onyx sand has raising the kh one degree per day. It end up being 10 kh at the end of the week before a big water change! I think I will have to move to another substrate...
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Geez. My suggestion to you is to use either Flourite Black or Black sand if you like the dark look of the substrate. Blasting sand is also a cheap alternative if you want that.
Quote from Seachem's website:
Onyx Sandô is a specially fracted, stable porous clay gravel for the natural planted aquarium. Its appearance is best suited to planted aquaria, but may be used in any aquarium environment. Being carbonate rich, Onyx Sandô provides an advantage to any plants able to utilize bicarbonates. Although ideally suited to planted aquaria, it may be used in any aquarium environment. Onyx Sandô is most effective when used alone as an integral substrate bed, but it may be mixed with other gravels. Gravel modifiers such as laterite are not necessary. Onyx Sandô is not chemically coated or treated and will not alter the pH of the water.
Being carbonate rich, Onyx Sandô provides an advantage to any plants able to utilize bicarbonates.
All aquatic plants can use bicarbonates that part is true, but what this isn't telling anyone is utilizing bicarbonates is energy intensive creating a net lose of energy and in the long run your plants will suffer. In short it takes more energy for plants to break the chemical bonds in bicarbonates than they get from it