KH question
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KH question

This is a discussion on KH question within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; --> I have a 40 gallon fresh water tank. I've had it for years and it has run very stable without major problems. I have ...

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Old 10-31-2010, 09:50 PM   #1
 
KH question

I have a 40 gallon fresh water tank. I've had it for years and it has run very stable without major problems. I have 4 clown loaches, 3 red eye tetras, and 4 neon tetras. The loaches I have had for ~5 years. My pH runs 6.8-7.0 consistently. Ammonia, nitrate, and nitrite are zero. Phosphate levels fluctuate, but respond to water changes and gravel cleaning. The GH fluctuates anywhere from 4 to 12. When I do water changes with RO water, the GH gets diluted and falls down. I have a set up to make the RO water. The Kh I am not able to detect. I have tried several different KH and alkalinity test kits and still I don't detect any KH. I don't have any pH fluctuations, so my pH is stable. Since my fish do well, I have not worried about the KH. Is there a desirable KH level? Should I bother trying to raise the KH (although I don't want to fool around with the pH).
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Old 11-01-2010, 02:08 AM   #2
 
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Quote:
Originally Posted by JGordon View Post
I have a 40 gallon fresh water tank. I've had it for years and it has run very stable without major problems. I have 4 clown loaches, 3 red eye tetras, and 4 neon tetras. The loaches I have had for ~5 years. My pH runs 6.8-7.0 consistently. Ammonia, nitrate, and nitrite are zero. Phosphate levels fluctuate, but respond to water changes and gravel cleaning. The GH fluctuates anywhere from 4 to 12. When I do water changes with RO water, the GH gets diluted and falls down. I have a set up to make the RO water. The Kh I am not able to detect. I have tried several different KH and alkalinity test kits and still I don't detect any KH. I don't have any pH fluctuations, so my pH is stable. Since my fish do well, I have not worried about the KH. Is there a desirable KH level? Should I bother trying to raise the KH (although I don't want to fool around with the pH).
R/O water will strip the minerals that make up your KH from the water (calcium,magnesium) and WILL result in very unstable pH unless you are adding buffering back to the R/O water used for water changes.
It is the KH and minerals that contribute to it's make up ,that resist's change in pH = stable conditions for the fish.
Most who use RO water add buffers (minerals) back to the RO water before using it ,or they mix the water for water changes ahead of time in seperate tub with tapwater of appropriate amount to maintain the desired KH and subsequently they are also able to maintain a stable pH.
Personally, I would not use RO water unless I absolutely had to for a specific species of fish.
I have three, two year old Clown Loaches that I purchased at approx two inches long. They are now five inches long and are kept in 75 gallon tank with tapwater that produces a pH reading between 7.4 and 7.6.
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Old 11-01-2010, 05:16 AM   #3
 
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Quote:
Originally Posted by 1077 View Post
R/O water will strip the minerals that make up your KH from the water (calcium,magnesium) and WILL result in very unstable pH unless you are adding buffering back to the R/O water used for water changes.
It is the KH and minerals that contribute to it's make up ,that resist's change in pH = stable conditions for the fish.
Most who use RO water add buffers (minerals) back to the RO water before using it ,or they mix the water for water changes ahead of time in seperate tub with tapwater of appropriate amount to maintain the desired KH and subsequently they are also able to maintain a stable pH.
Personally, I would not use RO water unless I absolutely had to for a specific species of fish.
I have three, two year old Clown Loaches that I purchased at approx two inches long. They are now five inches long and are kept in 75 gallon tank with tapwater that produces a pH reading between 7.4 and 7.6.
Above should read ,R/O will affect GH,KH as they are closely related. Hard to change one ,without affecting the other.
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Old 11-01-2010, 03:43 PM   #4
 
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I agree with 1077's advice.

But something puzzles me--if you do water changes using RO water, and the GH lowers as one would expect, what is causing it to rise again? Do you have any calcareous material in the tank, like rock or gravel/sand made up of limestone, dolomite, coral, marble? This is also affecting the pH I suspect, as in soft water the pH will lower over time due tothe natural biological actions.

Byron.
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Old 11-01-2010, 07:31 PM   #5
 
Thank you 1077 and Byron.

I usually use just the RO water, although I do have chemicals to add GH/minerals and KH to the water.

I have been remiss lately in my tank maintenance. For the past 6 months, I have done a 10-20% water change every 2-3 weeks. I changed the filter foam pads, phoszorb, nitrazorb, and zeocarb every 3 months, at which time I did a 50% water change (and vacuumed the gravel). The tank otherwise has been running well and the fish, especially the clown loaches, have been doing well. I have had no fish losses in several years (I lost a couple of neons back then).

Here are my tank's parameters before the big clean (gravel vacuumed a lot, filter material changed, and a 2/3rds water change:

pH 6.8
NH3 0.25
NO2 0
NO3 0
Phos 0
GH 13
KH 0
Alk at the bottom of the low scale

After the water change and adding in 1/2 the amount of Kent pH stable (to add alkalinity to the water), here are the tanks' parameters:

pH 7.0
NH3 0
NO2 0
NO3 0
Phos 0
GH 5 (was 4 yesterday soon after the water change; 5 today)
KH 0 (?if the test kit is correct)
Alk low-normal
Calcium 40
Magnesium 100

All fish are still doing well.

How much should I bother with the KH/alkalinity and the calcium/magnesium levels?
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Old 11-01-2010, 08:38 PM   #6
 
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To answer your last question directly, i.e., with no reference to the earlier part of the thread, my answer would be that it depends entirely upon the fish in the aquarium and the state of your source water. If the fish are suited to the source water, fine; don't even try to adjust hardness or pH, or KH, as there is no reason [notwithstanding any contrary advice you may read elsewhere]. If the fish need water significantly different from your source, and you have made the decision to acquire those fish, then adjust the source water naturally.

"Naturally" means with minerals (dolomite, marble, limestone) or coral if it needs raising, or RO water (diluting with rainwater, distilled water, and peat are other options for minimal volumes) if it needs softening.

And the point is significant variance; as 1077 alluded to with loaches. If you decided to house wild-caught discus, dwarf cichlids, pencilfish, etc., you would absolutely need soft, acidic water for their long-term health. I happen to have the latter type of fish (all wild caught from SA and SE Asia) and my tap water has near-zero hardness (GH and KH) and pH 7.0-7.2 [they raise the pH with something I can never remember but it is harmless to fish and does not affect hardness]. In my tanks which are fairly heavily planted and with 50% water changes every week without fail, the GH and KH are obviously zero and the pH runs around 6.2-6.4. I would never attempt livebearers without using dolomite/limestone/marble or coral to harden the water and raise the pH above 7. I did this many years ago, and for rift lake cichlids too.

While some of the marketed chemicals like Seachem's Stability may do the job, they are expensive long-term. And I have a premise that no chemicals should ever go into an aquarium except what is absolutely essential: water conditioner and plant fertilizer. A natural system will be more natural and stable if it is left to its own devices as much as possible.

To the earlier part of your latest post, I don't understand using RO water and then adding chemicals to raise hardness and pH. This means you are twice adjusting the water; and that means double the opportunity for trouble. If the tap water is too hard and has to be diluted with RO, work out the correct proportion and do that weekly with no chemicals.

I am not one who advocates raising KH in order to "stabilize" pH. An aquarium with a biological balance will naturally acidify over time; regular partial water changes work to maintain a stability to counter this, naturally, just as in nature--when it rains. Adding a small amount of dolomite or similar mineral also works to keep the pH from drastically falling, if that is a concern [it doesn't seem to in my tanks, with zero hardness]. The water parameters in the Amazonian streams varies a lot during the year, even during a day; this "stability" we often hear of is non-existent. And here I am not speaking of instability in an aquarium where the pH fluctuates wildly, that is dangerous. I have a diurnal fluctuation of .4 to .5 in pH every 24 hours, and that is natural (this occurs in nature) and harmless.

I've covered several bases here, so if anything is unclear, please ask.

Byron.
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Old 11-02-2010, 06:32 AM   #7
 
Thanks Byron.

Your point about using tap water and supplementing it with RO water to get to the desired parameters is noted.

I have well water. Usually it has the following parameters:

pH 7.6-7.7
HG 8
KH 0 (?if my tes kit is correct)
Alk mid-low (~0.8)
Phos 0
Nitrate 0 to 0.25

I am under the impression that the clown loaches, the neons, and the red eye tetras prefer a pH of ~6.5 to 7.0, so my tank running 6.8 - 7.0 is OK an the fish do well over the years to it. Do I need to try to keep the GH low for these fish? Again, the fish do well as is in the tank. I can do weekly water changes ~10%) and monitor the tank. I guess if the pH runs stable, then regardless of the KH or the Alk measurements, there must be good buffering capacity in the tank.

If i mix well water with RO water, is there a need to supplement the water with anything else? I don't want to add too much to the tank and disturb the fish. Since I know clown loaches can be sensitive to things, if they are doing well, they I assume the tank is doing well for the most part.

Again, thanks for your help.
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Old 11-02-2010, 12:27 PM   #8
 
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Quote:
I have well water. Usually it has the following parameters:

pH 7.6-7.7
HG 8
KH 0 (?if my tes kit is correct)
Alk mid-low (~0.8)
Phos 0
Nitrate 0 to 0.25
This is fine. A GH of 8 is on the border of soft/medium hard so that is fine. The KH I never worry about. With these numbers, I would expect the pH in the tank to lower slightly as the tank becomes established. However, the GH will not let it drop too fast in my experience.

Previously I mentioned my tap water has near zero GH and KH. In my 115g I have always had about half a cup of dolomite in the filter; it raises the GH from <1 to 2, and this has maintained a stable pH of 6.2-6.4 for 15 years. The other tanks without the dolomite have lowered to pH 5, which is fine for me because of the fish in them. The point here is that even with near zero KH (which it still measures in the 115g), the GH stabilizes pH. Coral will do the same. So I would continue to do weekly partial water changes with a mix of RO/well and monitor the pH [and probably the GH at least for a time].

Quote:
I am under the impression that the clown loaches, the neons, and the red eye tetras prefer a pH of ~6.5 to 7.0, so my tank running 6.8 - 7.0 is OK an the fish do well over the years to it. Do I need to try to keep the GH low for these fish? Again, the fish do well as is in the tank. I can do weekly water changes ~10%) and monitor the tank. I guess if the pH runs stable, then regardless of the KH or the Alk measurements, there must be good buffering capacity in the tank.
I think this bears out what I said above. With your fish, a pH below 7 is preferred, although they can manage above, but as it is working, give them what they prefer as you have been doing.

Quote:
If i mix well water with RO water, is there a need to supplement the water with anything else? I don't want to add too much to the tank and disturb the fish. Since I know clown loaches can be sensitive to things, if they are doing well, they I assume the tank is doing well for the most part.
I would not add anything. As noted above, the GH in my view is working to keep the pH stable. The less "stuff" going in the water, the better the fish will be.

Byron.
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Old 11-02-2010, 01:01 PM   #9
 
thank you!
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