Reply With QuoteMy ph with co2 is 6.3 and without co2 is 7.1 is it a huge ph swing?
My current Kh is 2, Gh is 5
How to increase KH without increasing ph?
My ph with co2 is 6.3 and without co2 is 7.1 is it a huge ph swing?
My current Kh is 2, Gh is 5
If your tank is not buffered by active soil or any other additives, then based on the kH and pH relationship table (one of the ways to estimate Co2 levels in the tank), your pH movement looks like it indicates a good Co2 level:Originally Posted by Kelvin247
Source: UKAPS.org
As you can see from the table, based on your tank water's pH 7.1 with kH 2, before Co2 injection the Co2 level is 5ppm... after Co2 injection when the pH becomes 6.3 with kH 2, the Co2 level is 31ppm (at optimal level).
Such pH movements are common in Co2 injected tanks, it usually not an issue for most fishes and shrimps (as long as the changes are gradual over the course of the day), unless the fauna are those super sensitive types which are particularly sensitive to parameter changes, then you may need to reduce the Co2 injection rate to moderate the pH movements.
Last edited by Urban Aquaria; 6th Oct 2014 at 13:31.
Sorry...what is ppm? i running my bubble at 1 per second for my co2
My reading i got it wrong....zzz
My ph with co2 is 6.4 and without co2 is 7.5
My current Kh is 1, Gh is 5
My TDS is 217
PPM = parts per million, its a unit of measurement for the concentration of substances in water.
For tanks with Co2 injection, around 30ppm level is usually considered optimal for plant growth, yet still relatively safe for most aquatic livestock.
Are you using any active soil substrate or additional pH/kH buffers in the tank? Those will affect parameter measurements.
oh ya i had almond leave in my tank for 1 day. and took out coz the ph reading dropping very fast
ANS soil
Last edited by Kelvin247; 7th Oct 2014 at 20:08.
ANS soil and ANS base
Thats interesting, i'd assume the ANS soil should be controlling and buffering the pH and kH lower (like with most active soil substrates)... your tank's pH seems rather high, maybe the soil's buffering ability has already been exhausted.
ANS soil is pretty neutral, it doesn't buffer like ADA does. OP, if you want to manipulate KH you can do so by adding CaCO3 (Calcium Carbonate/limestone/coral) or NaHCO3 (sodium bicarbonate/baking soda/seachem alkaline buffer). SG's tap water KH is about 1-2ish. Unless you want to keep fishes that require higher KH, there is little point in changing the KH value. Water organisms are sensitive to TDS/KH/hardness rather than PH swings because it affects their osmoregulation. PH swings due to CO2 of 1 degree is common even in nature, and most livestock aren't bothered by it. If you are trying to stabilize PH by increasing KH, I suggest not doing it; but if you want to alter it the above options are easily available.
Started the tank less then 3 month age. The soil should still be able to do what it should be doing
I keeping shrimps, oto, halfbeak with flame,java and taiwan moss.
Trying to put cation resin and peat moss. any advise on these? Heard they stabilize ph and soften water.
Yeah, thats what we would usually assume too... but different soil brands have different characteristics and buffering lifespans (depending on setup conditions like soil volume to water ratio, hardscape effects, water changes etc), so it can differ from tank to tank.
The higher the KH the more stable your water is when CO2 is introduced; i.e. your water has more buffering capacity. If you look at UA's chart above; the higher the KH, the more CO2 is necessary to drop the PH. So adding peat to soften your water (reduce KH) makes your PH fluctuate more when you use CO2. So the idea that peat stabilizes water in the PH sense is wrong, it does the reverse. However, peat does add humic acids etc which bind heavy metals, and some fish favor the acidity. And as mentioned above PH flux due to CO2 doesn't cause most species any harm, so you can use it if that is your intent, however, using too much of it can introduce a high level of organic acids that cause other problems.
Cation exchange resins generally exchange Ca, Mg ions for Na or H. This reduces your GH/KH but may increase your TDS (if replacement using Na; for every divalent cation(Ca,Mg), you are replacing with two monovalent cations(Na)). In short unless you are targeting something specific, and know the exact effects of what you are doing I don't recommend you use either of them. Our tap water is fine as it is. If you're keeping shrimp, you should be trying to maintain some GH instead.
There are some basic concept about water hardness we need to figure out first:PRACTICAL FRESHWATER HARDNESS Water hardness is of interest to aquarists for two reasons: toprovide the proper environment for the fish and to help stabilize thepH in the aquarium. There are two types of water hardness: generalhardness (GH) and carbonate hardness (KH). A third term commonly usedis total hardness which is a combination of GH and KH. Since it isimportant to know both the GH and KH, the use of total hardness can bemisleading and should be avoided.GENERAL HARDNESS General hardness is primarily the measure of calcium (Ca++) andmagnesium (Mg++) ions in the water. Other ions can contribute to GHbut their effects are usually insignificant and the other ions aredifficult to measure. GH will not directly affect pH although "hard"water is generally alkaline due to some interaction of GH and KH. GH is commonly expressed in parts per million (ppm) of calciumcarbonate (CaCO3), degrees hardness (dH) or, more properly, the molarconcentration of CaCO3. One German degree hardness (dH) is 10 mg ofcalcium oxide (CaO) per liter. In the U.S., hardness is usuallymeasured in ppm of CaCO3. A German dH is 17.8 ppm CaCO3. A molarconcentration of 1 milliequivalent per liter (mEq/l) = 2.8 dH = 50ppm. Note that most test kits give the hardness in units of CaCO3;this means the hardness is equivalent to that much CaCO3 in water butdoes not mean it actually came from CaCO3. Water hardness followsthese guidelines: 0 - 4 dH, 0 - 70 ppm : very soft 4 - 8 dH, 70 - 140 ppm : soft 8 - 12 dH, 140 - 210 ppm : medium hard 12 - 18 dH, 210 - 320 ppm : fairly hard 18 - 30 dH, 320 - 530 ppm : hard higher : liquid rock (Lake Malawi and Los Angeles, CA) General hardness is the more important of the two in biologicalprocesses. When a fish or plant is said to prefer "hard" or "soft"water, this is referring to GH. Incorrect GH will affect the transferof nutrients and waste products through cell membranes and can affectegg fertility, proper functioning of internal organs such as kidneysand growth. Within reason, most fish and plants can successfullyadapt to local GH conditions, although breeding may be impaired.CARBONATE HARDNESS Carbonate hardness (KH) is the measure of bicarbonate (HCO3-) andcarbonate (CO3--) ions in the water. In freshwater aquariums ofneutral pH, bicarbonate ions predominate and in saltwater aquariums,carbonate ions begin to play a role. Alkalinity is the measure of thetotal acid binding capacity (all the anions which can bind with freeH+) but is comprised mostly of carbonate hardness in freshwatersystems. Thus, in practical freshwater usage, the terms carboantehardness, acid binding, acid buffering capacity and alkalinity areused interchangeably. In an aquarium, KH acts as a chemical bufferingagent, helping to stabilize pH. KH is generaly referred to in degreeshardness and is expressed in CaCO3 equivalents just like GH. In simple terms, pH is determined by the negative log of theconcentration of free hydrogen ions (H+) in the water. If you add astrong acid such as nitric acid to water, it completely dissociatesinto hydrogen ions (H+) and its "conjugate base" or "salt", NO3- ornitrate. The hydrogen ions freed in the reaction then increase theconcentration of hydrogen ions and reduce the pH. Since nitric acidis the end product of the nitrogen cycle, this explains why aquariumpH tends to decrease and nitrates tend to increase over time. When the aquarium has some carbonate buffering in it, thebicarbonate ions will combine with the excess hydrogen ions to formcarbonic acid (H2CO3) which then slowly breaks down into CO2 andwater. Since the excess hydrogen ions are used in the reaction, thepH does not change very much. Over time, as the carbonate ions areused up, the buffering capacity will drop and larger pH changes willbe noted. From this it is clear why aquariums with low KH seemunstable - as acid is produced by biological action, the KH is usedup; when it is gone, the pH is free to drop rapidly as H+ ions aregenerated.ADJUSTING FRESHWATER HARDNESS If your local water is too hard for the fish and plants you desire,it can be softened. There are many ways to do this but some are moresuited to aquarium use than others. The best (and most expensive, ofcourse) is to use a reverse osmosis (RO) deionizer and mix theresulting water (GH=0) with tap water to get the desired GH. Peatmoss can be used to soften and condition the water for use in SouthAmerican cichlid tanks, but will add a slight tea color to the water.Peat filtering may be difficult to control. Peat should be boiledfirst to kill any unwanted organisms. Commerical water softening resin "pillows" can be used on a smallscale, but are not effective for larger amounts of water. Watersoftening systems designed for large scale home use (like bath water)are not suitable since they use an ion exchange principle: usuallysodium ions are substituted for calcium and magnesium ions and excesssodium is not desired in the aquarium. An even worse practice is touse a cation exchange resin in the hydrogen ion form and use it topull divalent ions out of the water. If the local GH is too low, it can be raised by adding calciumsulfate and/or magnesium sulfate. This has the drawback ofintroducing sulfates (SO4--) into the water, so care should beexercised. Calcium carbonate can be used, but it will also raise theKH (this is ideal for the lucky few who have naturally soft water).Various combinations can be used to produce the desired results. Carbonate hardness can be reduced by boiling the water (inpracticalfor all but the smallest aquariums; let it cool before adding to thetank :-) or by peat filtering. Carbonate hardness can be easily increased by adding sodiumbicarbonate. Calcium carbonate will increase both KH and GH in equalparts. One teaspoon (about 6 grams) of sodium bicarbonate (NaHCO3) per 50liters of water will increase KH by 4 degrees and will not increasegeneral hardness. Two teaspoons (about 4 grams) of calcium carbonate(CaCO3) per 50 liters of water will increase both KH and GH by 4degrees. Different proportions of each can be used to get the correctKH/GH balance dictated by the fish and plants in the tank. Since itis difficult to accurately measure small quantities of dry chemicalsat home, a test kit should be used to verify the actual KH and GH thatis achieved.FRESHWATER CHEMISTRY DETAILS In more detail, the pH of a buffered solution can be expressed by theHenderson-Hasselbach equation: base pH = pK + log ---- acidwhere pK is one or more "equilibrium dissociation constants" of theweak acid. In the bicarbonate and carbonate buffering cases, this is: HCO3- CO3-- pH = 6.37 + log ----- and pH = 10.25 + log ----- H2CO3 HCO3- Note that the pK values are affected rather appreciably by temperatureand chlorinity. If you plot the pH versus the ratio of base to acid,you will get a logarithmic graph something like this: 100% base ,--------- ,---------- / / H2CO3 | HCO3- | CO3-- 50% mix + CO2 |<- pH=6.37 |<- pH=10.25 | | / / 100% acid --------` --------` pH ...5...6...7...8...9...10..11..12...Bicarbonate buffering is effective over ratios from 1:100 up to100:1. This gives an effective pH range of 4.37 to 8.37, which, notcoincidently, defines the pH range of most aquatic life. If you add bicarbonate ions (for example, by adding sodiumbicarbonate or calcium carbonate), the base to acid ratio willincrease and the pH will increase. From the graph, the rate ofincrease will be determined by the pH you started with: at pH = 6.37,you will need a lot of bicarbonate ions to change the pH; at pH=7.5,you will need a lot less. (Note: the chemical equilibria of thevarious components of the carbonate system (CO2, H2CO3, HCO3- andCO3--) are very complex and are beyond the capability of the author tofully describe). The rise in pH that occurs when KH is added will be balanced to adegree by the dissolved CO2 in the water. Fortunately, CO2 is also aresult of the nitrification process and fish and plant respiration soit is readily available. The CO2 will form small amounts of carbonicacid and bicarbonate which will tend to reduce the pH. This mechanismgives us a way to regulate pH in the aquarium. If the pH of an aquarium is determined PRIMARILY by the carbonatebuffering system, then the relation of pH and KH and dissolved CO2 isfixed. You can change either KH or CO2 to set the pH. An automatic CO2injection system will measure pH and inject CO2 to lower it if itexceeds a set point. In this case KH is fixed. As the CO2 is used byplants and diffuses into the atmosphere, the pH will rise. Thecontroller cycles the CO2 on and off to keep the pH around a fixedvalue. The following chart shows dissolved CO2 levels in ppm for a range ofKH and pH values: degrees KH 2 3 4 5 6 +------------------------ 6.6 | 15 23 30 38 46 6.7 | 12 18 24 30 36 6.8 | 9 14 19 24 28 pH 6.9 | 7 12 15 19 23 7.0 | 6 9 12 15 18 7.1 | 5 7 9 12 14 7.2 | 4 6 8 9 11 7.3 | 3 4 6 7 9 7.4 | 2.4 3 5 6 7 7.5 | 1.9 2.5 3.5 5 5 7.6 | 1.5 2 2.5 3 4 7.7 | 1 1.5 2 2.5 3 7.8 | 0.9 1.1 1.5 2 2 7.9 | 0.6 0.9 1 1.2 1.6 8.0 | 0.5 0.7 0.9 1 1.2
Note that typical dissolved CO2 levels in a moderately stocked
aquarium will be in the range of 2-3 ppm. From the chart, it is clear
that almost any carbonate hardness will produce a pH in the mid 7
range unless extra CO2 is added. For a typical planted aquarium,
pH=6.9, KH=4 and CO2=15 ppm is just about ideal.
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