水草情迷

I use SERA ph minus to reduce the ph value of my tank.
But I don't know why the ph value can automatically increase back to around 7-7.2 from 6.8 or below after one day i use it and during the period the water has not been changed!
Any one can help, thanks.

哦,, 其實用化學品去降ph 真的不太好, 效果會來得快, 亦去得快.
你現時用的是什麼底沙, 有沒有其他石材, 現時的 ph/kh 是多少, 水喉水的 ph/kh 又是多少呢.

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Hi superctw,
I just test that ph is 7.2 and kh is 2 ar........terrible!
There are 3 sink wood and i use grass mud tablets.
Attached the pic for your reference.

Chemical is only effective if u have a bare tank, ie, discuss keeper use that to lower pH.
In planted tank, many factors affect the pH: the substrate, plants/plant remains, etc etc. For example, if your substrate contains lime (ie coral sand), then the H+ ions in your pH down chemical will quickly be used up. So your pH bounced back quickly.

thanks alan2002,
but it seen to be no such substance inside my tank?!

KH 2 is ok, try inject more co2 to lower the pH instead of adding chemical.

For my tank, kH is 4, if no Co2, pH is 7.6 (tap is 7.6), after inject co2, pH goes down to about 6.4~6.6.

The decrease in PH in my tank is due to CO2, cuz my substrate is old, ~ 3years, and i only use one part of soil, mix with 3 parts of fine gravel when i set the tank up. No ADA soils to lower pH.

To test how your Co2 lower pH, get some tank water aerate it using airstone, or shake it strongly. This drive out the co2, measure the pH. Then take another water sample from your tank, careful not to agitate it, measure the pH immediately. The diff is due to the acidity from injected co2.

Yes Sir,
but I have the problem of my DIY CO2.
It only works for 1-2 days after fill in the new material....
the gas is now generating very little ar.....

To boys:

Shouldn't be like that. My diy co2 usually last for 3 weeks.

To alan2002,
would you tell me your composition and the portion of the material and your diy equipment?
I must made some mistake

I use 2L coke bottle, 2/3 cup white sugar, fill bottle up to 2/3 full.
Put in 1/4~1/3 teaspoon of dry yeast. Add a pinch of baking soda (optional, but i add it to prevent mixture become too acidic in the coke bottle and kill the yeast, baking soda increase kH in the bottle, which acts as pH buffer).

Do not add yeast into hot water, they got kill. 35C is good, it gets the yeast to grow quick.

Make sure your diy is sealed properly. Use an airstone or a pice of bamboo chopstick (suggested by someone here) to breakdown the CO2 into fine bubbles.

Can I use 'gas wood', which is use in nitrate reducer for marine fish, instead of gas stone?
Thanks

I think it doesn't matter what u use to break down the bubble, as long as it doesn't required very high pressure to drive it.
Remember that diy co2 cannot produce very high pressure, unlike compressed gas tank.
I have tried ceramic diffuser, but think that a piece of bamboo chopstick is cheaper and better. When it get clogged with algae, i simply throw it away and put in a new one. The disposable bamboo chopstick can be obtained everyway, ie any fast food shop.