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-   -   KH and plants (http://www.plantedtank.net/forums/showthread.php?t=173262)

happi 04-18-2012 12:01 AM

KH and plants
 
i understand that you cannot messure the co2 levels when you have 0 KH, but does this have any effect on co2, i was reading somewhere Tom said that CO2 doesnt disslove very well under 0 KH. i always thought the lower the KH the better it is for plants. i just want to hear your opnions on this, i been keeping fish and plants under these condtions for long time now. i never really seen any fish stressed under these condtions, my plants are ok too, but not the best. i just want to see if anyone is sucessfully keeping plants under 0 KH

ray-the-pilot 04-18-2012 12:14 AM

I don't believe that anyone really has 0 KH because the pH of water with 0 KH would be about 4.3. I suspect that your KH is below the test limit of the test you are using. Anyway, I have no experience using such low KH water. I mix my RO with tap to get 4 deg KH.

happi 04-18-2012 12:29 AM

Quote:

Originally Posted by ray-the-pilot (Post 1824240)
I don't believe that anyone really has 0 KH because the pH of water with 0 KH would be about 4.3. I suspect that your KH is below the test limit of the test you are using. Anyway, I have no experience using such low KH water. I mix my RO with tap to get 4 deg KH.

now the real question is what if the KH was 0, how will the effect the co2 and plants. i know my test kit cannot messure lower than 6.0 PH, but API test kit for KH always change color with 1 drop. am sure KH levels are almost 0, because am using 100% RO.

AirstoND 04-18-2012 01:54 AM

It'll be interesting how the titration of an API alkanity kit actually works i.e. what is the chemistry theory? but a might be a patented chemistry process...

someone has a link?

Most calcium exists as a carbonate, but high hardness/low alkanity is indicative of a magnesium sulfate, phosphate or other non-carbon calcium compound?

jgb77 04-18-2012 01:57 AM

Try doubling the sample water used in the test kit. Instead of 5 ml, use 10 or even 15 then count the drops to get a more accurate measurement of your kh.
Also, I think even if using RO water, there will be some kind of buffer due to aquasoil or tannins etc.

John

dr.tran 04-18-2012 03:10 AM

My kH is 0 according to the test kits. Ofcourse its more like less than 1 but higher than 0. I dose ferts after all.

My pH is wicked low though. Like 5.1 sometimes 4.5 in my co2 injected tanks. Having said that, I never really had a problem with kH for plants. It was always more about not having enough of some nutrients for me.

Hoppy 04-18-2012 03:50 AM

I don't see how KH can ever be below zero. Intuitively I think the KH could only approach zero asymptotically, never quite reaching zero.

happi 04-18-2012 03:55 AM

Quote:

Originally Posted by Hoppy (Post 1824601)
I don't see how KH can ever be below zero. Intuitively I think the KH could only approach zero asymptotically, never quite reaching zero.

then why people are adding baking soda etc????

dr.tran 04-18-2012 03:57 AM

Quote:

Originally Posted by Hoppy (Post 1824601)
I don't see how KH can ever be below zero. Intuitively I think the KH could only approach zero asymptotically, never quite reaching zero.

No I don't mean less than 0. I mean 1< x >0. Less than 1 greater than 0 degrees of carbonate hardness. My test kit is accurate up to 1 degree. But I can't test in PPM which I suspect will give me a more accurate amount. Albeit a very low amount.

happi 04-18-2012 04:27 AM

Quote:

Originally Posted by dr.tran (Post 1824616)
No I don't mean less than 0. I mean 1< x >0. Less than 1 greater than 0 degrees of carbonate hardness. My test kit is accurate up to 1 degree. But I can't test in PPM which I suspect will give me a more accurate amount. Albeit a very low amount.

are you using 100% RO water??

Canuck 04-18-2012 12:08 PM

Quote:

My pH is wicked low though. Like 5.1 sometimes 4.5 in my co2 injected tanks
The pH of carbonic acid in normal atmospheric conditions is about 5.5. The pH of your tanks suggests that either pH test is off or you have stronger acids at work in your tank.

cradleoffilthfan 04-18-2012 01:49 PM

I never thought I would get a chemistry lesson at a fish forum lol. I never knew what the ph of carbonic acid was at normal atmospheric conditions......My kh is like 7 or 8 and I never had problems growing aquatic plants.....co2 was still effective, you would just need more of it. Also, aren't ph swings highly likely without any buffers? I never ever ever would use 100% RO/DI water. There are no buffers at all, nothing to keep the ph stable, that's why they sell buffers to add back to RO water to reconstitute it. I would at least keep the kh at 3 or 4 degrees. 0 kh sounds crazy to me.

happi 04-18-2012 02:40 PM

Quote:

Originally Posted by cradleoffilthfan (Post 1824921)
I never thought I would get a chemistry lesson at a fish forum lol. I never knew what the ph of carbonic acid was at normal atmospheric conditions......My kh is like 7 or 8 and I never had problems growing aquatic plants.....co2 was still effective, you would just need more of it. Also, aren't ph swings highly likely without any buffers? I never ever ever would use 100% RO/DI water. There are no buffers at all, nothing to keep the ph stable, that's why they sell buffers to add back to RO water to reconstitute it. I would at least keep the kh at 3 or 4 degrees. 0 kh sounds crazy to me.

i think PH swing was a myth, even if it was real, i don't think many people seen their fish died from it. they however killed them through overdose of co2.

cradleoffilthfan 04-18-2012 05:58 PM

Quote:

Originally Posted by happi (Post 1824982)
i think PH swing was a myth, even if it was real, i don't think many people seen their fish died from it. they however killed them through overdose of co2.

I suppose it very well could be a myth. I never tried the 100% RO/DI because I was told by everyone you would get huge ph swings due to lack of TDS's (Total Dissolved Solids). Without buffers, it would make sense that there would be a more unstable ph. Question: would the co2 cause a larger ph swing in straight RO water than water that had been reconsituted? And is co2 just way more effective in really soft water? Is that necessarily good for fish? And, is that good for the plants?

dr.tran 04-18-2012 06:17 PM

Quote:

Originally Posted by Canuck (Post 1824867)
The pH of carbonic acid in normal atmospheric conditions is about 5.5. The pH of your tanks suggests that either pH test is off or you have stronger acids at work in your tank.

I have ADA aquasoil. O kH and 0 gH.

Its right out of the tap. However, it must also be noted my water is slightly cooler than the average. Around 68-65 which means it can hold slightly more dissolved gasses than the normal room temeperture. So with that combined, I think it draws down my pH a little more.


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