# Zero KH - Do plants really like it ?



## kekon (Aug 1, 2005)

I'd like to get to know something something more about the subject. Some folks say that many plants grow very well when KH is set at 0. I've never kept such KH in my tank though. The lowest value i set was KH = 1.5. I also heard that very low KH was appreciated by Rotala Macrandra. However the main issue with zero KH is that it is very difficult to estimate how much CO2 is there in the tank. Do you have any experience with growing plants at zero KH ?


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## ashappard (Jun 3, 2006)

I dont know if my KH is zero point zero, but its low enough that test kits say zero.. Anyway - my plants do seem to like it very much. As far as CO2, I just go by a steady bubble rate. I really dont know how much CO2 is in my tanks. If I crank it up too high, the fish get stressed during the day. so I keep it below that amount. 

hope this helps. I've seen a few threads with dire warnings about letting KH go to zero. I have yet to suffer any misfortune, and have been running zero KH for quite some time. I do add GH to the tanks, need my calcium and magnesium


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## TortoiseBoy (Dec 30, 2004)

ashappard,
Can you tell me about how much light you have and what fertilization regime you use? Do you ever experience any obvious deficiencies in your plant growth? Thanks!


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## ashappard (Jun 3, 2006)

I have 2x96W PC fixtures over 19" 75G tanks. that works out to ~2.5wpg. I've had deficiencies in new shoots which I get rid of with additional GH and traces. Once I added that to my routine I no longer see any problems. 

I cannot answer if the need for more traces is because of very low KH or because of increased demand. My plants grow quite fast, and I mostly keep stem plants. I use TMG or Flourish for traces, but dry ferts on everything else. the regime varies between tanks and biomass, but its more or less just standard EI, additional traces (2x). 50% w/c every week with RO. +3 or 4 degrees GH at w/c. no KH. my toninas hate the baking soda. nobody else seems to mind that KH isnt being added.


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## kekon (Aug 1, 2005)

> my toninas hate the baking soda.


Do they get stunted and deformed when you add baking soda ?


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## TortoiseBoy (Dec 30, 2004)

Very interesting, ashappard. The reason that I ask is that my tap water is extremely soft and I wanted to see if you have had any of the same problems I have. Sounds like I arrived at the same conclusion that you did - adjust gh but not kh. My Toninas have the same problems  What form do you dose Ca in (eg. CaSO4? CaCl?)? Also, do you dose Mg, in what form and how often? Thanks again for taking the time to answer my questions.

Kekon, when I inadvertently increased my kh, my Toninas "melted" parts of the bottom leaves off. They got transparent and then rotted away. Interestingly, the problem started at the tips and moved toward the stem. I still have several stems of Tonina (sp. Belem) that have half leaves because only the tipward half of the leaf turned transparent and rotted. The remaining portion of leaf is still seemingly ok. Now that I know to avoid increasing my kh, my Toninas are back to growing and multiplying again.


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## kekon (Aug 1, 2005)

It seems that such plants like Toninas don't tolerate carbonates but i wonder if it's due to sodium which is introduced into the tank from baking soda. Raising KH to 3 we also add 25 ppm of sodium when baking soda is used for this purpose. Maybe the sodium is the culprit but i'm not sure.


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## ashappard (Jun 3, 2006)

kekon said:


> Do they get stunted and deformed when you add baking soda ?


they wither and die; melt more or less. new growth dies first, like tourtiseboy said.
and I dont think its the sodium, but I would like to know what it is about KH they dont like.

tourtise - I use gh booster I got from greg watson I dont remember the makeup of it. theres Mg in the GH booster, and I do add extra Mg and a bit of K at w/c. Maybe just superstition on the extra K/Mg I cant prove I really need it.


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## BryceM (Nov 6, 2005)

I reconstitue RO with NaHCO3 to a KH of 3 per Lamotte's alkalinity kit. I've been keeping three species of toninas for about 3 months now (fluviatilis, belem, & ?). So far they're doing ok, growing and dividing well enough. I must admit, the Na has always bothered me. I'd much rather use KHCO3, but NaHCO3 is cheap, easy to find, and seems to be working well enough so far.

My biggest block to lowering the KH even further is that I'd need to crank down my pH controller even lower to keep CO2 levels even. It's already set betwen 5.95 and 6.15. Justified or not, there is something in my brain that doesn't like pH numbers <6.

For the sake of completeness, I keep the GH around 5 by adding CaSO4, MgSO4, and a bit of CaCl2. Ca:Mg ratios are usually between 3:1 and 4:1, again per Lamotte's kit. Traces are TMG at 1 ml/gal/week and Flourish Fe at 0.5 ml/gal/week. I can post the exact formula if anyone is interested.


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## ashappard (Jun 3, 2006)

guaiac_boy said:


> My biggest block to lowering the KH even further is that I'd need to crank down my pH controller even lower to keep CO2 levels even. It's already set betwen 5.95 and 6.15. Justified or not, there is something in my brain that doesn't like pH numbers <6.


yeah, I had the same problem once my pH started dropping. It made me skittish. I dont have any sensitive inverts - but regular snails seemed fine, fish were ok, livebearers even kept breeding.

my SMS122s didnt have low enough setpoint, and I wasnt interested in jacking with slope/offset to trick it. the low pH made me a bit nervous also. Most of my tanks are at around 5.0 -5.3 pH, but nothing bad has happened. I got rid of all my pH controllers, dont have any drop checkers either. no offense to people who like the gadgets and controllers, I love the stuff also - I'm just not sure I really need to try to measure CO2. I have had the same bubble rate for about 7 months and that seems to be plenty good enough. I get prodded with quotes from books every now and then about low KH being dangerous, ph crash, biogenic decalcification (sp?) etc.

if it hadnt been for wanting to keep toninas / erios I'd never let go of KH, thinking I needed it. I hope someone does chime in on what it is about certain softwater plants and KH -- does it block the immobile nutrients? wish I knew more about botany and whatnot.


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## kekon (Aug 1, 2005)

As far as i know from hydropoonics sodium may influence Ca and K uptake but the question is how much sodium is needed to hamper Ca and K to be uptaken. I also use CaSO4, MgSO4 and some CaCl2 to set my GH to 6. To set KH i add NaHCO3 and KHCO3 and KH is about 3. 20 ppm K from KHCO3 gives KH = 1.5. Arguably KHCO3 is used in "Brighty K".


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