Hiya,

I'm a complete newbie to marine. I've been doing some research and hope to set up a 30G tank next year some time. It might sound really stupid, but here's what I can't ever seem to get my head around and I thought it best to ask.

Here's what I know. The PH needs to be between 8 - 8.4 for Seahorses (I know they're the most difficult fish to look after, but I have a lot time and energy to put into this, I understand about their care, but struggling somewhat with acheiving to understand marine water), what I don't know is how to acheive a PH of this value if I'm using RO water. I'm guessin RO water has a PH value of 7, right? I've genrally used tap water, but have been told I must use RO to keep Seahorses.

I know that using things such as proper PH chemical buffers is bad and using lemon juice etc on a regular basis is also bad. My tap water PH is 6.5 which is perfect for the fish I already have, so I've never really had to worry about this before. Would using crushed coral as a substrate or using a mesh bag of crushed coral in the filter help to increase PH and harden the water????

Could I store RO in big containers in the gararge, run a power head and air pump them with something in there to increase PH before I add the water to the tank maybe? I'd be storing the water for quite some time before I used it because there isn't a place close by that sells RO water and I don't want to have to drive miles every week when I do the 25% water change.

P.S I have bought marine aquariums for dummies, lol.

Thanks very much for any advice, I just can't seem to find this information on the internet. Maybe because it's such a stupid question.

The salt will rise the pH to between 8-8.5, and regular (small) water changes will make sure it statys that way. There are pH buffers to use if the pH drops for some reason.

Mattias

Your RO/DI water has a pH of about 7. Pure/Distilled water has a pH of 7. Seawater has a pH of 8.
Lemon juice will not help as it will lower your pH, as it is acidic and has a pH of around 2.

The trend of pH is downwards in marine aquaria due to excess CO2, nitrification etc. The oceans have natural pH 'buffers' in form of calcium, borate and other chemical compounds. You can buy good pH buffers although results will vary from tank to tank. I find the best way to maintain your pH initially is to ask on forums such as these about various methods.

A quick fix method to raise pH is adding baking soda. Be careful though, because the pH scale is lagorithmic and each number is a power greater/lesser than the current level.
Similarly, lemon juice is the quick way to lower an elevated pH.

Removing fish waste/uneated foods from the tank as well as regular partial water changes is perhaps the most commonly used and suggested method of balancing the pH level.

Adding trace elements can be done to target the cause of the pH drop.

Of course, the expensive option is to install a calcium reactor which does all the work for you.

Hope this helps.

http://www.my-marine.info/discussion/1/what-is-ph/#Item_1

That is my personal article on pH, gives you abit more or a technical explaination.