Help understanding KH and GH - The Planted Tank Forum
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post #1 of 23 (permalink) Old 03-18-2014, 12:25 AM Thread Starter
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Help understanding KH and GH

Hi all,

I was dosing EI via pre-mixed ferts from nilocg previously, but bought EI ferts from GLA and am trying now to learn and understand all aspects. I used a calculator and came up with my EI dosing which is fine far as I can tell. My questions right now is understanding GH and KH.

I had a large snail die off in my tank, almost all my bladder, ramshorn, and MTS died, the substrate looks like a shell graveyard. I have like 3 live ramshorns right now and their shells are bumpy and pitted. That made me think I had a calcium deficiency so I got a GH and KH kit to test the parameters. I did a 50% water change yesterday and my GH is 6 and my KH is 2. My understanding is that a GH of 6 shouldn't need a GH booster, but if that is the case why are the snail shells pitting and thin causing death? KH of 2 seems really low to me. How does this affect plants and the snails? The plants look health, some leaves have crinkles though and I do lose old growth on the bottoms of stems sometimes along with some rotala stems just breaking on their own low. I'm thinking this is clearly some sort of deficiency. Do I need to use a GH booster? Does KH need to be raised somehow?

From the faucet KH is 3 so slightly higher, and GH is the same at 6.

Edit: realized I left out ph. ph from the tank is 6.4 and from the faucet is neutral at 7.

Appreciate any insight and recommendation as to what I need to do for my water to A) help the plants out and B) be able to sustain the snails.

Last edited by bsantucci; 03-18-2014 at 12:51 AM. Reason: left out ph levels
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post #2 of 23 (permalink) Old 03-18-2014, 01:15 AM
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Definitely not an expert BUT:

It sounds like your ph is dropping due to a lack of kh to sustain it. You could try crushed coral in a media bag in your filter. A Tsp at a time.

Pitting on snails can sometimes be cause by a lack of calcium in their diet but maybe it's the slightly acidic condition in your tank? This I dont know.

What I do, lol, kindof know is a term called biogenic decalcification where plants turn to kh when there is a lack of available c02 in the water.

These are just ideas and thoughts to get you started. Hopefully they're on the right track and lead somewhere.

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post #3 of 23 (permalink) Old 03-18-2014, 01:19 AM Thread Starter
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Definitely not an expert BUT:

It sounds like your ph is dropping due to a lack of kh to sustain it. You could try crushed coral in a media bag in your filter. A Tsp at a time.

Pitting on snails can sometimes be cause by a lack of calcium in their diet but maybe it's the slightly acidic condition in your tank? This I dont know.

What I do, lol, kindof know is a term called biogenic decalcification where plants turn to kh when there is a lack of available c02 in the water.

These are just ideas and thoughts to get you started. Hopefully they're on the right track and lead somewhere.
Thanks I appreciate the reply.

I was under the impression the ph drop is from injecting co2? I definitely don't have a lack of co2, in fact I was blasting too much previously because I had surface agitation. I was running close to 40ppm of co2. I'm back down to near 30 now, or so says my drop checker.

I'll have to look into biogenic decalcification however like I said, plenty of co2 so I don't think it is that.

I'm confused as to whether or not I do in fact need to raise kh. I read some threads that say low kh is good, others saying moderate is good. So much mixed info on this. My ph is stable though, it raises at night when the co2 is off and drops a bit again when co2 goes on.

Last edited by bsantucci; 03-18-2014 at 01:21 AM. Reason: kh comment
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post #4 of 23 (permalink) Old 03-18-2014, 02:00 AM
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I wasn't aware you had C02 sorry.

C02 lowers your ph and creates carbonic acid if I'm not wrong. This in turn consumes your kh which is what helps to maintain a stable ph.

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post #5 of 23 (permalink) Old 03-18-2014, 02:03 AM
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I wouldn't be concerned at all with your KH. Fiddling with KH only causes more work for no gain. Your GH seems fine for most anything, assuming your test is accurate. If you suspect low GH it won't hurt anything to add GH booster to raise it 1-2 dGH. Plants do use Mg and Ca. As far as why your snails are dying I have no idea. Maybe because they are lacking in their diet not the water parameters? My experience with snails is how to properly smash them against the glass lol.
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post #6 of 23 (permalink) Old 03-18-2014, 03:07 AM
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The acidic water is harming the snail shells.
To raise the pH add carbonates in some form, such as baking soda or potassium bicarbonate.
Your very low KH is allowing the pH to be controlled by other things in the tank, in this case the CO2.

You can still add CO2, and the plants will benefit from it. But when the KH is a bit higher then the pH will be closer to neutral, and the snails should be OK.
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post #7 of 23 (permalink) Old 03-18-2014, 03:19 AM Thread Starter
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Originally Posted by Diana View Post
The acidic water is harming the snail shells.
To raise the pH add carbonates in some form, such as baking soda or potassium bicarbonate.
Your very low KH is allowing the pH to be controlled by other things in the tank, in this case the CO2.

You can still add CO2, and the plants will benefit from it. But when the KH is a bit higher then the pH will be closer to neutral, and the snails should be OK.
How much baking soda would I need for a 46 gallon tank to go basically a half point higher? I'm not sure if the fertilizer calculators calculate for baking soda since I'm on my phone right now. I'd assume I would need to do this right after water changes weekly?

Thanks for the response I think this is definitely it. Do I need this gh booster at all that I just bought or is my gh Ok where it is?

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post #8 of 23 (permalink) Old 03-18-2014, 03:38 AM
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1 teaspoon of baking soda added to 30 gallons will raise the KH by 2 German degrees of hardness. When my tanks have 'bottom of the test' pH (that is 6 or lower) then the pH comes up to about 6.2.

You can use simple math to add more or less baking soda to any size tank to get the result you want.

1 tsp.... 30 gal..... 2 dKH
1 tsp... 45 gal.... 1.3 dKH

You will have to test and see what that does to the pH. Carbonates are not the only thing that can affect the pH.

When you are making changes to the minerals in the tank go slow. A little today, wait a few days, then a little more. The fish need time to adapt.
2 dKH change in one go is safe for fairly delicate fish, but I do not do larger changes even for hardier fish.

Monitor the results to see how stable they are. In many tanks various processes remove carbonates, so the level will drop over time. You might be OK correcting this once a week.
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post #9 of 23 (permalink) Old 03-18-2014, 11:54 AM Thread Starter
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ok thanks so much for the guidance. Is there anything I can do to to keep my ph up on a more permanent basis rather than doing this weekly? I'd assume though once I get it back up to neutral from this dive that even with the 50% changes as long as I keep up on it I wouldn't have to to such drastic dosing, right?

So my gh of 6 is good though? no need for additional gh booster?
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post #10 of 23 (permalink) Old 03-18-2014, 12:39 PM
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I can only offer you my experience in this arena.

I do all of my chemistry (adjusting KH / PH and GH in a five gallon bucket for a 5 gallon tank) before I put it into the water in the aquarium. I use Seachem products exclusively for this process.

Quick important note, KH is very important when it comes to your water chemistry as it is directly related to your PH value. PH will fluctuate more with a low KH and less with a higher KH. Buffering your GH with a higher KH is desirable; however, a strong PH buffer does reduce the amount of usable carbon your plants will get from CO2 injection. I use Seachem Flourish Excel as a carbon source supplement in addition to CO2.

At start, with the water right out of the tap, my PH is at 7.6 (stays that way after letting water sit for 24 hours), KH at 20 ppm (.35 dH), and GH at 30 ppm (.5 dH).

Adjusting the GH is a simple process, 1 to 1.5 cups of water with 1/4 to 3/8 Equlibrium mixed in, then poured into the bucket. That raises my dH to 3.5 to 5.5. I adjust as necessary depending on what I am trying to keep in the tank, be it fish, shrimp, plants or something else (less for softer water, more for harder water). I like this method better than using crushed coral as I get very precise results.

KH / PH is a little more involved. First thing I do is bring the KH and PH using acid to alkaline buffer of 1.5 to 1 (for me, that's 3/16 tsp acid buffer to 1/8 tsp alkaline buffer). That drops the PH to around 6 and bumps KH up to 40 ppm (2.25 dK). From there, I walk both back up using a reversed ratio of 1 acid to 1.5 alkaline until I hit the mark I am looking for. Once complete, I have a well buffered PH value, greatly reducing PH fluctuations. This method also yields very precise results as compared to using baking soda.

If you were to do it this way, it would be better if you adjusted a small amount, say 5 gallons at a time, then slowly introducing the new water into your tank during water changes.

If you try this, always mix it up in a separate bucket rather than in the aquarium. Also, if you mix it up in water of less than 5 gallons, mix the acid and alkaline buffers independently, then pour each into your water bucket separately.

Hope this helps.
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post #11 of 23 (permalink) Old 03-18-2014, 01:37 PM Thread Starter
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Thanks for the reply. I'm a little confused though rpadgett37 as to why you bottom out the ph first then bring it up? I looked at Seachem Alkaline and it seems it's really similar to baking soda, but baking soda would be cheaper, no?

How long does the baking soda, or any calcium bicarbonate hold up in water before I'd need to add more? I assume once stable, adding a bit each week would maintain this?

Another thought I have, would a ph controller for my co2 work better for me or would that not provide enough co2? I do have an apex system and just ordered a ph probe so I could have more precise, constant ph readings. I can use that also to control the co2, but again, not sure if that is the best route to run co2 for plants? Since my tap comes out at 7-7.2 for ph, maybe the ph controller would allow me to keep it around there? Just shooting ideas out here.

Quote:
You can use simple math to add more or less baking soda to any size tank to get the result you want.

1 tsp.... 30 gal..... 2 dKH
1 tsp... 45 gal.... 1.3 dKH
Diana, wouldn't 1tsp in 45g equal 1dKH? I'm just trying to understand the math. If 15 gallons more are in my tank which is half the 30, wouldn't that just half the dKH number completely? Meaning, my tank I could do 1.5tsp to raise 2dKH?

While I'm thinking about it Diana, the main purpose I'm trying to do this actually is for my snails. I like the trumpet snails keeping the substrate turned over and I like ramshorns all over. The fish are completely fine with my acidic water. Rather than mess with ph and kh which I keep reading you shouldn't do, would just adding more calcium to the water to increase GH allow my snails to thrive in acidic conditions?

Last edited by bsantucci; 03-18-2014 at 02:28 PM. Reason: dKH quote/snail question
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post #12 of 23 (permalink) Old 03-18-2014, 07:30 PM
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Using crushed coral in a filter bag or sprinkled among your substrate lasts much longer and is easier. There are calculators out there that can tell you how much to add for whatever effect your are looking for. Baking soda works but may need adjustments after water changes.

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post #13 of 23 (permalink) Old 03-18-2014, 08:08 PM Thread Starter
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Using crushed coral in a filter bag or sprinkled among your substrate lasts much longer and is easier. There are calculators out there that can tell you how much to add for whatever effect your are looking for. Baking soda works but may need adjustments after water changes.
Thanks! From what I read though it seems injecting co2 and snails just doesn't mix. My plants and fish are happy and healthy so I'm just going to give up the snail pursuit. I just liked having MTS to turn the substrate.

I don't want to mess with a stable ph and have more issues down the road.
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post #14 of 23 (permalink) Old 03-18-2014, 09:08 PM
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Originally Posted by bsantucci View Post
Thanks for the reply. I'm a little confused though rpadgett37 as to why you bottom out the ph first then bring it up? I looked at Seachem Alkaline and it seems it's really similar to baking soda, but baking soda would be cheaper, no?
First I'll say that when trying to adjust PH, you need to focus on changing the KH of the water. Wherever KH goes, PH will follow. Not the other way around. Sorry for the confusion there.

To answer your question, because my starting KH value was so low and had no buffering capacity, and since my target PH was 6.8 from 7.6, there wasn't any choice but the drop the KH down and let the PH plummet with it. Under these circumstances, the only way to get to PH 6.8 with a strong KH buffering capacity was to go down, then bring it up again. As I mentioned, I use the Seachem acid and alkaline buffers for the task, and it is a personal preference for me. Baking Soda will do fine for raising your KH, but you have to watch it. I am not sure what to use to lower the KH.

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How long does the baking soda, or any calcium bicarbonate hold up in water before I'd need to add more? I assume once stable, adding a bit each week would maintain this?
Not sure but it doesn't matter. Regular water changes will keep your KH reasonably stable provided you are doing all you need to in the aquarium.

NOTE: Your replacement water should have the same water parameters as what is in the aquarium, matched as closely as possible. If you are going to continue using baking soda or anything else, be sure to do it in the replacement bucket and not in the aquarium.

Quote:
Another thought I have, would a ph controller for my co2 work better for me or would that not provide enough co2?
CO2 is another ball of wax, and there is no such thing as a PH controller for CO2. Basically, CO2 will always want to lower KH because of some chemistry going on in the water that I understand a bit but can't explain very well. Remember that where KH goes, PH will follow. The only thing you can control here is the amount of CO2 you are infusing into the tank. Fewer bps lessen the pressure on KH, while more bps increase the pressure on KH. The higher your KH when you start introducing CO2, the more stable your PH will be.

Here's a link to a series of articles that explain water chemistry better than I can. Lots of good stuff in here.

http://www.fishbeginner.info/home/aq...-what-to-know/

Hope this helps, and FY, snails and TOO MUCH Co2 don't mix. Snails do just fine with CO2 in the water. They aren't my specialty so I don't know if there are some snails more sensitive to it than others; however, I've never read anything that says CO2 is toxic to snails unless there is too much of it in the water. And finally, there is nothing wrong with adjusting your KH and PH values. Just don't do it in the aquarium with your critters. I always do mine in the replacement water prior to doing a water change.

Last edited by rpadgett37; 03-18-2014 at 09:24 PM. Reason: Left something out
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post #15 of 23 (permalink) Old 03-19-2014, 01:43 AM
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Diana, wouldn't 1tsp in 45g equal 1dKH?
No.
1 tsp in 60 gallons = 1 dKH.

from 30 to 45 gallons is only 50% increase over the 30 gallon tank, so it dilutes the baking soda only about 2/3.

These numbers are only a close approximation. Tanks vary in their actual capacity, first because they are almost never what the label says, and second because substrate and other things subtract, and a canister filter or sump will add volume.

I suggest you add about 1/2 to 2/3 of the amount you think you need and measure the results.

Do not bother the GH. GH of 6 degrees is just fine.

Quote:
Buffering your GH with a higher KH is desirable;
Huh? GH measures calcium and magnesium.
KH measures carbonates.
Not the same thing, nor does one buffer the other.

KH and pH are linked. Carbonates and bicarbonates buffer the pH. Yes, CO2 is in this equation, too. Raise the KH and the pH will usually rise. Not always. Other things in the water can also affect the pH. But these don't register on the GH test.
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