Importance of KH in a planted tank?

[PeterGwee]

Hi guys, like to have the topic open up for discussion after a brief chat session with charles at biotope regarding CO2 level (Hope you don't mind charles []). He mention that his planted tanks has pH of 5.8!!! and he did not add any KH up or baking soda stuff which amazes me (The fishes in the tanks look healthy and full of life even at such acidic level [:])...alas forget to ask the pH before CO2 injection coz he is using ADA soil -- pH lowering effect.. Oh..his style seems to be the same as DEA huh..LOL [] . Okay..I like to find out how you think of such acts and any possible risk? (pH crash as in theory...no fish death in their tank due to CO2 injection leh).

[TTL]

Haa..

At last got a thread so interesting.

My planted tank got a PH of 5 during initial setup with 4 discus in, now after 1 mth or so? stay at PH 6. I using peat moss as part of my base fert mix with JBJ.

the funny thing is my SAE, Yamatos & Malayan shrimps are ok, apisto ok and 4 discus ok too. the discus especially like it so much at PH 5 then now at PH 6. My KH are at 3 with CO2 injection?

Erm.. is this related not?[]

[PeterGwee]

Kekekeke...with the use of peat moss, I doubt the KH value you are getting is accurate. []

[TTL]

hmm.. izzit? I using Sera brand for KH measurement.

The first drop it turn blue, 2nd drop turn pale yellow & 3rd drop turn yellowish... So, my KH shld be 2 and not 3?

Not really concern wif it cos my plants growing mad and fish are healthy.

[PeterGwee]

Yup..if it ain't broken don't fix it. (Most test kit we use are basically general guides..unless you are using stuff like Lamotte which is not available in Singapore).

[TTL]

Actually don't really understand how KH will affect plants or fish.

I measure KH is becos most of AQist say must measure & KH must be ard 3 to 5.. So just follow the trend without wondering why?

But I do know how to measure CO2 lvl using the PH & KH chart... kekekeke...[]

[PeterGwee]

KH doesn't really affect fish directly..it prevents pH from falling drastically upon CO2 injection from lets say pH 7.2 to 5.8 or less in a very short time thus causing shock to fishes...(However, some people say in nature such things happen whereas some say the opposite thing! Who is right? Haha...

[CK Yeo]

erm... actually, KH is only for buffering to prevent the pH from crashing. With regards to plants, nutrient absorption can be affected by extremes of pH at either end. e.g. Fe. It is not really a very very important factor, cos plant usually have their means to deal with it.

FOr fish, it really depends on where the fish comes from. I think SEA peat forest fishes thrive in slightly more acidic water (Budak, can confirm?). We are just trying to mimic the fish's natural environment. In fact, from what I read, Rasboras will only spawn in acidic water... and rumor is that this is also the case for Altums, which maybe why altums never spawn in our tanks, because we think the pH (5?) is considered "too low" for them? Eyons ago, before I found out about KH, my water is so acidic that it always falls out of range of my pH test kit. Fish (Rasboras) were fine, so were the plants.

So, i feel that, in a planted tank, there is really no need to be anal about extactly what KH is the water or the exact pH. The important thing is the CO2 level, which is determined by measuring the KH and pH.

Or maybe we should ask the fish we keep what pH they prefer?

ck

[PeterGwee]

Nice one CK..but the problem is how to measure CO2 level when the KH is almost zero? I sure like to know how DEA and Charles manage to keep their fish alive with injection of CO2 without supplementing KH? (Charles told me he added about 2 bubble per second to the "plants selling tank" -- with fish in it of course.

[budak]

Current discussion at Aquabotanic suggests that certain aquatic plants (e.g. E. stellata and Blyxa, maybe also Tonina and some crypts) NEED KH below 3 to thrive.... while for other plants KH isn't too material. For fish, the idea I have read is that blackwater (Asian or Amazonian) fishes are adapted to conditions where Ca/Mg is minimal; thus any increase in KH results in clogging of their blood vessels/breeding vents with a Ca lining. For the eggs, it's fatal as the Ca effectively encapsulates the fry alive. Low pH is also anti-bacterial, so these fishes tend to develop infections more easily at tank pH levels.

Certainly, blackwater habitats (like those for rasboras) are known to be very very soft and acidic. Kasselmann reports the Rio Negro with KH and GH below 0.1 degrees pf hardness and pH 3.7-4.3, while Tasik Bera in Malaysia has readings of 0.17 for KH and pH of 5.33. in both habitats, nitrate, nitrite and NH4 are below barely detectable. Humic acid level is recorded as "very high." for altums and heckels, i really suspect nothing short of such extermely acidic, mineral-deficient waters will prompt spawning.

[Nicky]

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For fish, the idea I have read is that blackwater (Asian or Amazonian) fishes are adapted to conditions where Ca/Mg is minimal; thus any increase in KH results in clogging of their blood vessels/breeding vents with a Ca lining....
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Err... I may be wrong, but isn't KH=cabonate hardness?
I thought Ca and Mg affects GH and not KH.
If I'm right, then increase in KH does not directly imply that Ca or Mg has increased.

[naturetan]

I'm glad that such discussion has been brought out. Thought I'm the only weird one to ask such question[] ..

Personally, I've been keeping my Neon fishes and plants with 0KH for 3 months. So far they're doing good, sometimes the Neon fish could be seen chasing each other like a beautiful dance(mating?), and they're adapting well to such low levels. My plants are bubbling like crazy with 1bps. This rate is more of a trial & error by looking at the plant health and bubbling.

The issue of increasing my KH level recently comes when people talks about PH swing, which I'm quite skeptical, so I start to take reading, before and after the plant photosynthesis. All the time, reading either 6 or below PH. No such drastic swing to more than 6.

Finally , I give in when the saying goes: Better fix it before its too late. Don't really like to see any casualty due to my mishandling or ignorance. However, now i'm relieved to hear that it's not really a necessity to increase my KH, saving me the trouble of introducing foreign particle like sodium![]

[Plantbrain]

While you might find pH's of 5 and 0 KH in nature, maintaining it a tank is another matter.
KH is the HCO3- ion essentially. No buffer, then removing the acid(CO2) will greatly cause a rapid change in pH. Also, at very low KH's, the pH measurements become very difficult to measure and special probes are required. Many of the measurements from very softwater regions are incorrect since they are done with normal pH probes etc. A buffer resist the changes in pH and allow an easier more accurate measurement of pH.

Peat/humics effect the relationship also. This effect can be measured although few ever do this.

Fish/critters IME can handle very wide ranges of CO2 and pH. O2 seems to be much more the issue for them. They live in very soft water one season, then hard the next dry season.
Shrimp seem prettyb tolerant of high CO2 levels IME.

Simply because you find a fish or a plant in soft water does not automatically assign it's optimal living condition to that environment. They adapt to make it through a rather harsh variable environment. Rainforest are not extremely stable, they change, the area where intermediate distubances that remove organisms will be where the greatest diversity exist.

I can travel but 10 miles to find the same plants/fish growing well in total opposite environments here. Very soft acidic water, loaded with tannins and the other clear hard water. The plants do better in general in the hard waters with more CO2.

The softwater areas are more variable in this region as a rule.
Regards,
Tom Barr