Water Used For Brackish

[lisa_perry75]

Hi there,
Atm I use tap water because it is hard alkaline (about pH 8 ) imagine liquid chalk... As I was thinking about doing a planted tank as well I was thinking about using different water. I can source some filtered really really pure stuff (probably alot like RO, pH 7 very low GH and kH). My question is
If I use this and add salt, do I need to add anything else to buffer it? I'll probably be using a substrate with a little buffering capability like onyx sand... I may well be adding Co2 as well, does this affect anything as I know it can lower the pH.

 

[Fella]

Hi there,
Atm I use tap water because it is hard alkaline (about pH 8 ) imagine liquid chalk... As I was thinking about doing a planted tank as well I was thinking about using different water. I can source some filtered really really pure stuff (probably alot like RO, pH 7 very low GH and kH). My question is
If I use this and add salt, do I need to add anything else to buffer it? I'll probably be using a substrate with a little buffering capability like onyx sand... I may well be adding Co2 as well, does this affect anything as I know it can lower the pH.

If you want to create a brackish environment, why would you use the RO water when you have a high PH water from your tap?

Why do you want to add salt to the water?

 

[lisa_perry75]

Because I would like to do a planted tank and the plants don't like too high pH/gH/kH, I wasn't sure what the fish need...

I have a pair of knight gobies, 2 figure 8s and a mono at 1.005 currently.

 

[raptorrex]

i think you may be supprised:
http/www.fishforums.net/index.php?showtopic=22604

RO is expensive, very wasteful and in this instance not actually needed. most of the plants in the link will handle it, getting ones that like brackish, is more tricky.

 

[nmonks]

To be honest, if you want the "underwater garden" look, brackish isn't the way to go. While lots of plants will thrive at low end brackish, most will do better in freshwater, and CO2 fertilisation becomes a lot less important the lower the pH.

Marine salt mix is "self-buffering" since it contains quite a lot of carbonate hardness. This is what brackish water fish like. If you're after a planted brackish water tank, you may as well just get plants that thrive under such conditions. Most of them extract the carbon they need from the carbonate and bicarbonate, so CO2 fertilisation isn't terribly important. You do tend to get swings in pH if plant growth is very rapid though, because the plants are reducing the KH, so keeping an eye on pH is important. A weekly water change of 50% should prevent this happening to any serious degree.

Cheers, Neale