Help regulating pH, KH, & GH

[fl4ian]

I have a moderately (heading toward heavily) planted 100g aquarium. I have some corkscrew val, wisteria, glossostigma, and java moss. I have moderately light bio-load. I am not running any type of CO2. However, I am running two Marineland Penguin 350's (HOB filters) and I have heard that they are actually probably putting CO2 INTO the water (as opposed to off-gassing it). I have several bags of Flourite in the aquarium, I have Matrix in some mesh bags in the spare area in each filter. I use Flourish, Clarity, Stability, & Prime as appropriate.

I have tap water that is:
Ammonia: 0
Nitrite: 0
Nitrate: 8
GH: 9 degrees
KH: 1 degree
pH: 7.1

My tank water continues to drop in pH (apparently because of the lack of KH - and maybe in conjunction with the "over-filtering" - please correct me if I'm wrong). I tried to increase the KH by adding baking soda, however around a third of the amount that I calculated it would take, ended up raising my KH by only 2 degrees, and shot my pH from 6.2 to around 7.5.

My goal is to have a pH around 6.8 - 7.0, with about 6 degrees of KH and GH. I think that at those values the water parameters would be fairly stable. Are these values reasonable and achievable?

I've heard crushed coral might do the trick, however, now I've found Neutral Regulator and Alkaline & Acid Buffers. I'm not sure what to do at this point. I'm looking for minimal effort and low cost solution.

Please give me your guidance.

[Tech Support JS]

fl4ian,

Thanks for contacting us. First off, since you have a planted aquarium, you will want to stick to carbonate based buffers (Acid and Alkaline Buffer) and stay away from phosphate based buffers (Neutral Regulator, Acid and Alkaline Regulator, etc).

Secondly, crushed coral is made up primarily of calcium carbonate. What the theory behind this is that the CaCO3 will dissolve and give you a carbonate source to buffer your pH. Unfortunately, Calcium carbonate is generally insoluble at a pH above 6.5, thus would not be very useful to an aquarium with a pH of around 7.0. You might as well just have rocks down there at that point.

I'm not sure about your Penguins putting CO2 into the water, but the logistics of that doesn't seem like it would make sense. The impact of the return water would indeed increase the amount of CO2 dissolved, but that would then increase the amount of CO2 that dissipates (there is a detailed explanation of chemical laws, but just trust me). Regardless, the amount of CO2 added would not effect your pH too much, only slightly (at the level that would be dissolved form the return) so I would probably put that out of your mind for now.

Your numbers are very reasonable to achieve, and the best way to do that would be to use the Acid and Alkaline Buffers in conjunction at the specific ratios listed on the bottles (remember the ratios are for dosages, not direct ratios.. i.e. it would be one dose of Acid to 2 doses of Alkaline). You will have to give it some time to establish a buffer system, so be patient. In water changes, be sure to add the buffer at the ratios (only for the water change volume) before you add it to your tank, that way you are adding buffered water. I hope this helps, and let us know if you have any other questions, we'll be happy to help!

[fl4ian]

Thanks for the quick response and the insight on the Penguins and the crushed coral. Let me ask a few follow-up questions:

1) once I achieve a stable pH and stable KH, how long will they reasonably stay that way? I mean, at first I will be adding daily to achieve the correct balance. How many weeks of daily dosing should I anticipate (in ordering product) before I achieve some stability? You mentioned that I would need to be patient and give it some time to establish the buffer system - how long do you think is a fair amount of time to assume here. And after it becomes stable, then obviously I wouldn't be dosing daily anymore. Would it be weekly, bi-monthly, monthly? I realize that's probably a difficult question to answer as there are so many variables...

2) would it be advantageous to reduce the GH prior to trying to stabilize the pH and KH? I've seen products like API's water softener pillow that are supposed to drop the GH. Ideally, I'd like the bulk of the GH to come from the KH. KH because I need it (KH) in sufficient quantity to keep the pH stable, and other than that, I'd like to have as soft as water as I can - so I'm thinking about trying one of those pillows to remove the bulk of the GH. Then, as the KH comes up as the buffer, the GH will be much more closely matched to the KH. Is my logic sound here? Does this seem reasonable (to try to remove a fair amount of GH prior to stabilizing? Do you have any experience with water softening pillows? Are there any other methods for removing excess GH?

3) Beside using RO or DI or distilled water, all of which would need to be purchased, is there a better way to condition the tap water to remove the GH prior to putting it in the tank to account for evaporation (or during partial water changes for that matter [in which case, I'd add the buffers also])?

Thanks again for the insight.

[Tech Support JS]

I'll be happy to answer your questions:

1) Every question you asked in the first paragraph is going to be something that varies greatly on a tank-to-tank basis. The length of time it takes to establish a buffer system will depend on the details of your water contents, but in general should not take excessively long. A buffer works to help prevent changes in pH, but that doesnt mean that, say, a great addition of acid to a buffered solution wouldn't lower the pH very quickly. Say I have buffering capacity "X" for one tank with a small bioload. Over time, the pH will change because of the constant acid produced from the organisms. If I have the same buffering capacity "X" with a greater bioload, the pH will shift faster, so you dosing regime will depend on that (in addition to your water chemistry)

2) GH wont typically play too big of a role in pH issues. To some extent, if you have an extremely high GH, it could effect your buffering capacity somewhat. Some of our products have a side effect of softening the water, but none are what you would want to use for your tank. So you may want to investigate on your own about that... I personally use RO water and have never needed to soften water. If you prefer lower hardness in your water, that there is nothing wrong with that, but it wont necessarily help you out too much in your pH issues.

Its important to note that GH and KH are completely separate entities. KH is a measure of your carbonate hardness and measures the amount of carbonates (both bicarbonate and carbonate) someone has in their tank. GH mainly measures the mineral content (magnesium, calcium, potassium). So it is impossible for any of your GH to come from your KH, or vice versa. Its also important to note that KH is not a definite measure of your buffering capacity; again it only measures the amount of carbonates in your tank (which are, in fact, good buffers, and thats why people equate it with buffering capacity). Carbonates and bicarbonates typically want to keep your pH fairly high because they have high pKs, which is the measure of the dissociation constant and can explain why such a little amount of bicarb boosted your pH and not your KH. So re-evaluating your numbers, at a pH of 7-ish you may not be able to achieve a KH as high as 6, but dont worry, its just chemistry. Your water will still be well buffered.

3) To condition the water I would suggest using Prime, which has a beneficial side effect of removing heavy metals. To soften the water you can use whichever method you choose (from above). Definitely add the buffers to the replacement water before you add it to the main water

I hope this information is useful to you and have a great day!

[fl4ian]

I did not know that GH and KH are NOT related. I thought that GH was a total hardness value that included the KH values. In other words, I thought if I had a KH of 1 and a GH of 9, and I added 5 degrees of KH, it would mean that the GH would AUTOMATICALLY go to at least 14, which I specifically don't want to do. What you are saying is the opposite of this, which is great to know.

If I get my KH from 1 to say 5 (assuming a pH of 7.1 and GH of 9):
1) would the pH remain relatively stable?
2) what increase should I expect to see in the GH if any (by raising my KH from 1 to 5)?
3) do pH and KH reach some sort of equilibrium in nature? in other words, everything else equal, if the KH is 9 the pH will be 8.2 or if the KH is 3 then the pH will be 6.2 or something like that? that is what I was getting at when I asked if pH 7-ish and KH 6-ish was reasonable... I don't know what to shoot for realistically.
4) at what KH is water considered to be adequately buffered? what would be a KH value that would be considered to be not adequately buffered?
5) does anything use up the GH? I know that KH is used up to buffer the acids produced by nitrification, etc., but is there a normal process that consumes GH? or does it just continue to accumulate?
6) also, is it true that in order to test tap water properly, it must sit for 24 hours (or sometimes I hear that it needs to be aerated for 24 hrs) prior to testing?
7) what is the difference between baking soda and the Alkaline Buffer? would the alkaline buffer (or baking soda + wonder shells) increase the GH?

[Tech Support JS]

I'm glad to help!

1) This would be a good indication that your pH will be stable.
2) You shouldn't see an increase in GH.
3) You cant really have a set ratio or anything like that. I'll try to keep it short: There is Carbonates and Bicarbonates have a certain pKa, to which they will want to keep the pH at (which are higher than you want it to be). So no matter how much you add, that only means that you will be getting closer and closer to that number. So if you have a higher amount, the stronger they are going to pull.

Imagine your carb/bicarb buffer system as workers on a roof hoisting up a piano (the 'height' of which would be your pH) against gravity (which would be the acids trying to lower your pH). The more guys you have pulling, the higher up the piano will go, and if you have enough, they will lift it all the way up to them, but not higher. If you only have a few guys, your "piano" will not raise up too high, but the few guys trying to pull it up will keep it at a steady height instead of allowing it to fall (since they aren't strong enough to raise it).

4) That would depend on the tank parameters and what pH you want. But generally anywhere between 2-6.

5) Plants can use up the ions that make up your GH, but would probably do so at such a slow rate that you wouldn't notice.

Again, I hope this helps and thanks for posting!

[fl4ian]

sorry for all the questions - the more i find out, the more questions I have - thanks for your patience in educating me. Thanks especially for the analogy of the piano lifters...

I had two more questions in my last reply that you didn't address (#6 & #7), I may have edited too late for you to get those - I'm not sure. But I would like your insight on those. In number 6 I'm referring to testing tap water for pH, KH, GH, ammonia, nitrites, & nitrates.

The only other question at this point would relate to (and be a clarification of) #4 in my last reply - at my target pH level of 6.8-7.0 range (give or take), where in the 2-6 KH range would I ideally be shooting for? 4? 5+? At what point does KH become unhelpful, dangerous, or bad in my pH range?

[Tech Support JS]

Sorry I missed those two at the end, I guess the edit didn't refresh in time...

6) You may want to let your tap water sit for 24 hours to allow everything to equilibrate with the atmosphere, you would probably get better results.

7) Baking soda is sodium bicarbonate, Alkaline Buffer is a proprietary blend of bicarbonate salts as well, and at a much higher quality percentage than typical baking soda. Alkaline Buffer will not raise your GH, only your KH.

*4) (revisited) Because KH, while a good indicator of buffering capacity, is a measure of your carbonates, and not a measure of your buffering capacity as a whole, this number will vary. An exceedingly high KH (8,10,12) will cause ionic imbalance, while a low one (0.5, 1), in your case, would probably indicate inadequate buffering. Your KH will prob. be on the low end, ~2.

Thanks for the post and have a great weekend!

[ForexWop]

Hi, cool post. I have been wondering about this topic,so thanks for writing.

[Tech Support AN]

You are very welcome! That is why we are here and let us know if you have any questions we can help out with! :)