# Co2/ph/kh Table



## Danny (26 Jan 2018)

Going off my API kh test results of 10 and ph of 6.4 with the Co2 table I'm getting a result of 119.4ppm co2... 

How can that be right with Tetras and shrimp living happily in the tank.....


----------



## Zeus. (26 Jan 2018)

Danny said:


> Going off my API kh test results of 10 and ph of 6.4 with the Co2 table I'm getting a result of 119.4ppm co2...
> 
> How can that be right with Tetras and shrimp living happily in the tank.....
> 
> View attachment 112900


It's not right OFC. Test kits are not accurate esp at hobbist level. Most folk don't use them at all. Using a Drop Checker with a freash solution is best option for finding [CO2] and that's only gives an approx value. The fish snails etc will also tell you if it gets too high hanging at the surface, too high and dead fish OFC

Sent from my Moto G (4) using Tapatalk


----------



## Danny (26 Jan 2018)

Zeus. said:


> It's not right OFC. Test kits are not accurate esp at hobbist level. Most folk don't use them at all. Using a Drop Checker with a freash solution is best option for finding [CO2] and that's only gives an approx value. The fish snails etc will also tell you if it gets too high hanging at the surface, too high and dead fish OFC
> 
> Sent from my Moto G (4) using Tapatalk


Yeah I know test kits are not exactly reliable but thought I would see how the results measured up, I've tweaked the co2 to the point of gassing the fish and reduced it to a point they are happy enough at so know I'm at the tank limit for it.


----------



## ian_m (26 Jan 2018)

The table is for distilled water and carbonate hardness, not tank water. 

You can really use it for pH changes to gauge change in CO2 ppm. Which handily works out 1 unit pH drop for 30ppm.


----------



## Danny (26 Jan 2018)

From what I've read a higher kh leads to a more stable ph, would it be worth going to 50/50 RO and tap to reduce it to potentially 5 or does the risk of an unstable ph negate that?


----------



## ceg4048 (27 Jan 2018)

Danny said:


> From what I've read a higher kh leads to a more stable ph,


Yes, but so what? Stable pH means nothing and will not result in either a healthier tank or healthier fish/shrimp.



Danny said:


> would it be worth going to 50/50 RO and tap to reduce it to potentially 5 or does the risk of an unstable ph negate that?


Use RO or 50/50 or whatever combination you like based on issues such as reducing TDS or for breeding or for reduction of contaminants and so forth. The worst reason for  not using RO is the fear of unstable pH.

Cheers,


----------



## Danep (17 Apr 2018)

Sorry for dredging up a 3 month old thread but thought I'd offer my 2 cents...  

to sum up this post without addressing your specific situation which I'll do in my next post, for anyone else who stumbled on this and is still confused what to do when balancing a tank follow these steps- 

1) Ensure the filter bacteria are established and can handle the bioload - ammonia and nitrites are steady at 0 (can be done with either pure ammonia or a few cheap fish to start the cycle)
2) Balance kH and gH to the fish you plan on keeping - generally you want it around 4-8 degrees kH and 4-12 gH for most fish (kH generally won't kill your fish but will definitely stress them out if too far off and will affect your pH, also having a soft water fish in hard water is usually better than a hard water fish in soft water but be sure to look into the requirements for your particular fish, they're readily available online).  
3) Balance nutrients for your plants (NPK) if you have them (it's generally better to have too many nutrients than too few, a lack of any one nutrient will quickly cause algae blooms, however also consider that phosphorus and potassium will raise your gH value)
4) Adjust pH for your species of fish - like kH most fish will be able to survive in a wide range for pH, it's not nearly as important as most people make it out to be.  One thing that most people don't realize is that kH measures carbonate (CO3-2) and bicarbonate (HCO3-). Ions with a negative charge will raise your pH and these particular ones also act as something called a buffer and will make it very hard to bring your water back to neutral.  Basically if you try to neutralize a solution with these in it by adding acid it will seem to have little effect until the amount of acid approximately equals the amount of carbonate and bicarbonate at which point it will swing quickly.  So it will result in harmful pH swings even if you only add a little at a time.  If you have high pH and high kH it's better to try to remove some of the carbonate with things like driftwood or peat moss rather than try to neutralize your tank with an acid which is what chemicals like vinegar or pH down would do.  If you have large swings in pH it's probably due to a low kH value where any variation in water chemistry results in a large pH change.

Other notes on gH and kH - these values constantly increase after water changes, as water evaporates out of your tank pure water is being removed and the ions measured by gH and kH will remain in the tank.  If your tap water has high gH and kH already and you top it off with tap water instead of doing actual water changes these values will keep getting higher.  It's better to try to estimate how much water you lost to evaporation vs what you removed during cleaning etc and mix the replacement water to attempt to match a ratio close to that.  So if you lost 2" of water depth in a 40 gal breeder tank before you removed any water, the replacement water would be 2 gallons of distilled or RO and the rest would be tap water to match what you removed.

That comment leads to my last one, if your tap water parameters are anywhere in the ballpark of ideal leave the tank alone.  Remember any adjustments you make to the tank will need to be done to the water change water going back into the tank, and adjustments made for evaporation fertilizer addition etc.  Instead of constantly testing and retesting your aquarium parameters and trying to micromanage your levels with chemical's and additives find a way to maintain close parameters easily.  If you have unsuitable tap water you may have to look into an RO system but most people's tap water will do just fine, just remember that additives need to be put back into RO water to provide essential nutrients so 0 kH/gH is not necessarily the goal.


----------



## Danep (17 Apr 2018)

In response to your original question either you're aquarium water is incredibly hard or you performed the test incorrectly.  Generally gH should be around 10 at a maximum (about 200 ppm) and kH should be much lower - closer to 3 degrees or 50 ppm.  If your kH levels really are 10 your water is incredibly hard and you're probably better off starting with RO or distilled water and adding nutrients back in for water changes.  More likely though you made an error in the testing process, either by confusing gH solution for kH solution, not capping and shaking the test tube after each drop or not putting full drops of the solution into the test tube each drop.  There also could have been an issue with the pH test test procedure although that one's more straight forward.  Since kH is a measurement of ions that are alkaline in solution and yours is high, it doesn't make any sense for your aquarium to be acidic over all at 6.4 unless there was some other chemical additive involved, even though CO2 would make neutralize the high kH value slightly you wouldn't be able to dissolve enough C02 into the water to see a pH below 8 at that kH concentration.  If you do decide to go with a drop checker as noted above be sure to only use RO/DI or distilled water in that as using your water with a KH of 10 (if it is) would turn green at a pH of 7.1-7.4, so if you're trying to maintain your current pH at 6.4 for some reason it will rise if you adjust until the checker is green.


----------



## dw1305 (19 Apr 2018)

Hi all,





Danny said:


> API kh test results of 10 and ph of 6.4





Zeus. said:


> It's not right OFC. Test kits are not accurate esp at hobbist level.


I agree with @Zeus, they are fairly unlikely parameters, and you certainly don't have 119 ppm CO2. If you don't add CO2 you will have somewhere between 0.5ppm (the theoretical equilibrium value with atmospheric CO2) and the <"usual assumption of 3ppm">.  





Danep said:


> ammonia and nitrites are steady at 0 (can be done with either pure ammonia or a few cheap fish to start the cycle)


Welcome, we don't tend to recommend either "sacrificial" fish, or ammonia addition, as "cycling" techniques. We have a slightly different approach to cycling to most forums, this is because we only keep planted tanks and that more recent scientific research (on biological nitrification) has shown that a much wider range of organisms are involved in nitrification than was originally realized. Have a look at <"Filter cycling?"> and links. 





Danep said:


> however also consider that phosphorus and potassium will raise your gH value


The PO4--- may raise pH and alkalinity, but it won't change dGH, which is a measure of multivalent cations (like Ca++). Same applies to K+, it is a base but it doesn't change dGH, because it is a monovalent cation.

If you add a salt like potassium chloride (KCl) it has net neutral effect on pH, because it is the salt resulting from the reaction of a strong acid (the source of the Cl-) and a strong base (the K+) ion. Phosphate is a weak base, so PO4--- containing compounds can be either acidic or basic, which is why you can have <"phosphate buffers">. 





Danep said:


> So it will result in harmful pH swings even if you only add a little at a time. If you have high pH and high kH it's better to try to remove some of the carbonate with things like driftwood or peat moss rather than try to neutralize your tank with an acid which is what chemicals like vinegar or pH down would do. If you have large swings in pH it's probably due to a low kH value where any variation in water chemistry results in a large pH change.


That is the one, as you get towards pure H2O pH is less and less useful as a measure. The only real way to lower hardness is to use a low hardness source like rainwater or RO, a lot of <"our members"> have very hard water and <"produce stunning results">. 





Danep said:


> Generally gH should be around 10 at a maximum (about 200 ppm) and kH should be much lower - closer to 3 degrees or 50 ppm. If your kH levels really are 10 your water is incredibly hard


 It is a bit different in the UK, a lot of us will have water with ~20 dGH/dKH, most of our water tends to have about the same dGH and dKH values, which is largely to do with our aquifers being limestone (CaCO3) that hasn't undergone <"dolomotization">.

The derivation of both dGH/dKH <"is a bit strange"> but because it is based on the amount of CaO. If all your hardness is derived from CaCO3, both 1dGH and 1dKH are equivalent to 17.86 ppm CaCO3.

cheers Darrel


----------

