Calling All Experts

[Dave Spencer]

I added crushed coral in the filter and my Kh has stabilized at either 3 or 5. (It varies by tank depending on whether CO2 is added.)

CO2 does not affect the KH.

I am really curious about those who have 0 Kh. Can you tell me what their water change procedures are that they don't have fish loss? Maybe it is something other than Kh but I agree with you that Ph changes are a minimal, in any problem.

Greg

I change 50% weekly, straight from the garden hose. The temperature drops about 4 degrees C without any adverse effect on the fish. Many fish seek out the cold stream of water.

In winter I need to add a little warm water to stop the tank temperature dropping too much.

Dave.

 

[aaronnorth]

I didn't understand your last little post answering something to kcharley

answering this:

Aaron,

I am really curious about those who have 0 Kh. Can you tell me what their water change procedures are that they don't have fish loss? Maybe it is something other than Kh but I agree with you that Ph changes are a minimal, in any problem.

Greg

bacteria are very tough, i agree,
but my point being people worry about pH crashes, which 'should' cause bacteria die-off because the kH is low. The more people i talk too, the more this becomes a myth, along with Nutrients causes algae theory,
I am not doubting the buffering capacity, as i know that is true, just bacteria die-off as an indirect result.

and get reading that book

thanks.

 

[LionessN3cubs]

I didn't understand your last little post answering something to kcharley

answering this:

Aaron,

I am really curious about those who have 0 Kh. Can you tell me what their water change procedures are that they don't have fish loss? Maybe it is something other than Kh but I agree with you that Ph changes are a minimal, in any problem.

Greg

bacteria are very tough, i agree,
but my point being people worry about pH crashes, which 'should' cause bacteria die-off because the kH is low. The more people i talk too, the more this becomes a myth, along with Nutrients causes algae theory,
I am not doubting the buffering capacity, as i know that is true, just bacteria die-off as an indirect result.

and get reading that book

thanks.

well see thats a different color of horse than I was talking about. I NEVER made mention of bacteria die off because of low ph or KH. The PH/kh I was discussing had to do with PH shock in my fish...not the bacteria

 

[drobbyb]

If this is all true, then why are people experiencing delayed cycle times and stalled cycles on their fishless cycle. If none of it matters, then there should be no problem, right?

Not trying to pick a fight, just trying to understand.

 

[LionessN3cubs]

If this is all true, then why are people experiencing delayed cycle times and stalled cycles on their fishless cycle. If none of it matters, then there should be no problem, right?

Not trying to pick a fight, just trying to understand.

Stalled cycle definately happened to me last time. I'd had my ammonia dropping down in 12 hours for like 3 days...nitrite spike happening blah blah blah...then all of a sudden NADA...until I did a water change and got my PH back up...which is when I found out about KH and ph crashing and had to dump baking soda in the tank so it didnt happen again.

 

[aaronnorth]

well see thats a different color of horse than I was talking about. I NEVER made mention of bacteria die off because of low ph or KH. The PH/kh I was discussing had to do with PH shock in my fish...not the bacteria

i know, i was replying to waterdrops post about different pH's.

If this is all true, then why are people experiencing delayed cycle times and stalled cycles on their fishless cycle. If none of it matters, then there should be no problem, right?

As WD mentioned, the problems usually occur on "new" colonies, whereas the more developed bacteria you will probably get little die-off and they will adapt to the water chemistry.
So it probably does matter when cycling, but once you have a mature colony, then no, it doesnt matter IME.

 

[kcharley]

CO2 does not affect the KH.


I change 50% weekly, straight from the garden hose. The temperature drops about 4 degrees C without any adverse effect on the fish. Many fish seek out the cold stream of water.

In winter I need to add a little warm water to stop the tank temperature dropping too much.

Dave.

Hi Dave,

Thanks for the response. I don't understand the chemistry but my experience is CO2 does affect the KH. I didn't think it would but my KH went to zero (without crushed coral in the filter) very quickly (a day) after starting the CO2. Since I seem to need to match KH to prevent fish loss at water changes, I added the crushed coral to the filter. The KH in my CO2 tank stays in the 4 to 5 range while the KH in my other tanks (with crushed coral in the filters) holds at 3. Someone, I don't remember who, claimed that the carbonic acid dissolves the KH. I don't understand that, as it seems to me if it is liquid it is already dissolved. But the CO2 does keep a higher KH level once the crushed coral is added.

Do you know if the plants in a CO2 tank use KH? Somehow I got the impression they did in a non-CO2 tank and that was why my KH dropped slowly in those tanks (before adding crushed coral). Maybe the plants use KH regardless of CO2 and use more of it due to the faster growth in CO2 tanks?

Do you know the KH of your tap water? I'm guessing its zero or close to it.

I agree fish seem to like cooler incoming water. I'll try the 4 - 6 degree F instead of the 2 - 4 I have been using.

Thanks again.

Greg

 

[kcharley]

Hey Lioness,

Any water changes recently? I'm curious how it is going. Well, I hope.

Greg

 

[drobbyb]

Ok. Would be nice to test and see.

 

[Dave Spencer]

Hi Greg,

Thanks for the response. I don't understand the chemistry but my experience is CO2 does affect the KH. I didn't think it would but my KH went to zero (without crushed coral in the filter) very quickly (a day) after starting the CO2.

The reaction is:
H2O + CO2 <=> H2CO3

H2CO3 is carbonic acid, which will lower the pH. As you know, adding CO2 lowers the pH, and it is this principle we use on CO2 drop checkers.

You say that you are seeing your KH moving to zero when you add CO2. What you are really seeing is the alkalinity moving to zero, because KH test kits do not measure the KH of the water, they measure the total alkalinity. These kits measure the alkalinity because it is easier to measure than KH (I assume), and the majority of the alkalinity comes from the carbonate hardness. Alkalinity and carbonate tend to be used as the same term, when this isn`t really the case. If your KH kit consists of one bottle, you are measuring total alkalinity.

A lot of people add sodium bicarbonate and see their KH increase. This is not the case either, as carbonate hardness is the measurement of carbonate and bicarbonate ions that are calcium and magnesium, not sodium. What they are seeing is their KH kit measuring a rise in the total alkalinity, supplied by the sodium bicarb.

Alkalinity is a measurement of the buffering capacity of the water, defined by its ability to neutralise H+ ions without altering the pH. KH is a measurement of the temporary hardness, not the buffering capacity. As a general rule, most of the buffering is supplied by calcium and magnesium bicarbs, so measuring the KH gives a “reasonable” figure for the alkalinity.

Do you know if the plants in a CO2 tank use KH? Somehow I got the impression they did in a non-CO2 tank and that was why my KH dropped slowly in those tanks (before adding crushed coral). Maybe the plants use KH regardless of CO2 and use more of it due to the faster growth in CO2 tanks?

I think plants can utilise KH as source of carbon in certain conditions. I can`t remember whether they do it via the production of RuBisCo, but I would have to read up on that again. I know Vallisneria sp can sequester carbon via the KH, but will still choose CO2 injection as their first choice for carbon.

Do you know the KH of your tap water? I'm guessing its zero or close to it.

My tap water is circa 2dKH, as measured at work. I never worry, and I do not add sodium bicarb, certainly not in a tank with fish in. Plus, of course, plants are generally not very fond of sodium.

I agree fish seem to like cooler incoming water. I'll try the 4 - 6 degree F instead of the 2 - 4 I have been using.

My fish seem to love the stream of cold water. I don`t believe the majority of our fish come from rock steady environments, and mine seem to get excited at the change in parameters a water change brings. I do keep an eye on the drop in temperature during winter, though.

Dave.

P.S. I wish I hadn`t started this, as my water chemistry has become a bit sketchy since I first did any way back when I joined the power industry.

 

[aaronnorth]

I think plants can utilise KH as source of carbon in certain conditions. I can`t remember whether they do it via the production of RuBisCo, but I would have to read up on that again. I know Vallisneria sp can sequester carbon via the KH, but will still choose CO2 injection as their first choice for carbon.

they can use carbonates as a source of carbon if that is what you mean?

 

[kcharley]

Thanks Dave, Thanks Aaron,

Okay, I have the single solution KH test so I'm measuring total alkalinity. So the CO2 isn't affecting the KH so much as it affects alkalinity, right? That would make sense because of the carbonic acid. Aw heck, I don't know and probably don't need to know. What matters is I found something that works for me that I don't lose fish at water changes. I just hope Lioness finds something that works for her.

Aaron's comment reminded me of what I was remembering. That is, in the absence of CO2 plants will use carbonates to help them make rubisco. They stop using it in the presence of CO2. That is why I expected the KH readings to stay the same when I first added CO2. I didn't realize that the CO2 would neutralize some of it so it was going to change anyway.

With all this said, I am going to go buy some plants for the garden. They will have to get their CO2 from the air.

Greg

 

[JenCliBee]

Well Aaron gave me the link and i must say very interesting, pretty much answers most of my questions, so thanks to all