Backyard Aquaponics
A place to discuss aquaponics

beach shells are fine once washed.

Is there much limestone around where you are? Limestone (calcium carbonate) is another alternative to raising pH that may be easy to get locally - its readily available in some parts of Thailand...

Is something like baking soda available there? Ya don't want to be using it much since it adds sodium but to initially get the pH up to say 7 over a couple weeks and then the shells or limestone should be able to hold you steady.

Another option might be wood ashes ashes. (Kinda the old fashion way of getting lie for soap.) Making sure they are not from something poisonous or from charcoal brickets. You would need to be rather careful mixing ashes with some water. Don't get splashed or get it in your eyes as it could be caustic and burn you. You would probably need to dilute it quite a bit so as not to cause a dangerous pH spike in the system. Perhaps test the effect of a small amount in a bucket of system water to help you calculate how much you would need to use to bring the pH up by say .25 at a time. Then wait a day or two before dosing again that same amount.

Good luck.

+ you'd get potassium

The ashes sound good, I'll give them a try.

as TCLYNX stated, the liquid product MAY be quite caustic, so use caution (mix a known ratio in a bucket of fish water and measure the PH rise. then work out how much you need.

we dont want the ashes experiment to become an "ashes to ashes, dust to dust" experiment for the fishies LOL

maybe do some extra research too...........

http://en.wikipedia.org/wiki/Lye
http://en.wikipedia.org/wiki/Potash

plus any number of traditional soap making websites. PM janetpelletier, she may have some tricks

I've got heaps burnt rice husks, would it be a good idea to throw a touch of that in?

i wouldn't know. specifies hard wood. suspect it might not have the desired effect.

Plachon ,, Shell grit available at feed stores ....., used for chickens.

Plenty of " Kai" there.

Can't think of any other alternatives ....., Isaan water is very high PH so I've never had this problem.

You could test the ashes for the husks. Carefully mixing with some system water in a bucket (wear eye protection and be careful) and measure the effect it has. No matter what you do, start with very small amounts of anything untried or unproven. Always change pH very slowly!

The problem is I can't find anywhere in Bangkok selling it because there's no chicken farms in the city.

I've found a company close to me that makes calcium carbonate, however I'm not sure if it's the right stuff because most of it seems to be for the plastics industry, here is a link to the products.