I put in a large mangrove last night. I have been running my pH at 6,6 with a KH at 4. This morning when I checked pH it was 6,4 (usually it is 7,1 before the Co2 kick's in) and the KH had dropped to 3. The water was a little bit brown.

I just cleaned the mangrove with running water before i dumped it in the tank. It had some leftovers of javamoss on it, so I figure it has been in a tank before.

The pH/KH chart doesnt mach anymore (the Co2 wont kick in as it is set on ph 6,6 so it cant be 35ppm of Co2 as the chart says)

What causes this and what should I do to get back on track again...?

Vidar

Ok... I've been searching a bit more and have found out it must be tannin. In a post on APC it can look like a bit tannin is ok, but what to do with that Co2..?

It's a bit big for boiling....

I've posted a pick to show the dimension. The tank is 145cm long, 40cm high and 40cm deep.

You can measure the CO2 by using PH only, eliminating the effect of non carbonate alkalinity and acidity from other than carbonic acid. Just take a sample of the water in the tank, let it sit in the open for a few hours for the CO2 to dissipate down to the atmospheric level, then measure the PH of that water. To get 30-40 ppm of CO2 in the tank you need to decrease that PH by 1.0. You can use this as the controller setting, but it will only be accurate until more tannins get into the water, so you almost have to repeat this every day or so until the water in the tank is stable, then start all over when you change water. One caution: while a 1.0 drop means 30-40 ppm of CO2, a 1.3 drop means twice that much, and a 0.7 drop means half that much. This makes measuring PH accurately very important.

Thanks VaughnH...! I guess pushing the pH further down wont harm the fish...? I'll take a sample from the tank tonight so I can see how low I must push the pH to get a decent co2. I calibrated the probe today with fresh buffer and it was off with 0,1 so the pH is actually 6,5 and KH 3,5 (I counted Tetra drops in 10ml samplewater instead of 5ml to get more accurate KH)

I have five Clown Loaches and for Pearl Gouramis. It looks like they prefer a pH at 6,4 decreased by tannin instead of 6,5 by Co2. The Clowns have been more active and full of "jokes" all day, and tonight they waited for the wafers at the front of the tank before the lights went out. Usually they wont eat for hours after the lights (and the co2) shut off.

As things are right now the tank runs like a non-co2 tank, so would it hurt to slowly increase the co2 by the tannin removement caused by weekly 50% waterchanges? I've been fighting some real bad BBA before I got my co2 stable at 30-35ppm.

There was some pearling a few hours before the lights went out.

Vidar

Not sure if this is any help to you or not, but..

I have heard people mention before that a piece of bogwood would drop the ph so maybe that is the reason if the mangrove has the same properties as bogwood?

It doesnt help you but it may help to explain why the change with ph?

Mangrove wood should add Salt and hardness, not depress the pH as a general rule.

If it's a live tree, then it might lower the pH but it should not be much.

Regards,
Tom Barr

It's not actually mangrove.... Sorry bout that one. Mangrove is a common sales-name on roots and driftwood for the aquarium here in Norway. Usually its mahogny or teac. (dont know if thats the right translation)

The ph of the sample rised from 6,5 to 7,2. Yesterday I slowly pushed ph down (while watching the fish) to 6,2 and everything seems fine.

Pearling started a bit later this evening. I guess its because the tea colored water takes some light, but I hope that will improve over time with the waterchanges.


Problem solved and thumbs up!

Thanks again VaughnH!


Vidar

Now if only I could take my own advice! I finally gave up on the PH test kit and bought a PH probe - a Milwaukee pH53. So, I calibrated it and tested the tank water. The reading settled down to 6.34 (love that extra decimal point). I took a tank sample and let it sit for 4 hours, sloshing it every hour or so. Read the PH and got 7.25. Not bad, huh? Then I remembered Tom's advice about the interference the ballast can cause. So, I turned off the light and retested the tank. Got 6.64! Drat! Why does fate work so that every damn mistake we can make always overstates the amount of CO2 in the water? Is this known as the 98th corollary of Murphy's Law?

Letting the sample sit for 4 hours is not enough -- try 24hours and test that one again. I'll bet you get higher than 7.25.

CO2 is the biggest pickle in the hobby.
We all think it's fine etc and often it is, then we have a growth issue or a algae bloom and think nutrients, not the CO2.
Then we add lots of light.
Then we want slower easier to maintain growth.

We want it it all?

But CO2 will really nail you good.
It's surprising that given the relationship and corrleation to so many issues, folks would have long known this and suggest remedies.

Maybe I have special IR inflared CO2 googles?
Hehe

Actually I just watch the plants and crank CO2.

Regards,
Tom Barr