Best Practices: Kh, Ph And Raising Them

[waterdrop]

Thanks guys, these last two messages are quite helpful on the practical side. I have a nice bag of florida crushed corel waiting in the shed in case I decide to use it (probably should have for this second phase of fishless cycling, might have gone faster if indeed they like a higher pH!)

It will be very hard deciding whether to move away from my standard tap water for my permanent setup. My pH is 7.6, my KH is 0-1, NH3/NH4, NO2, NO3 are all zero from the tap. I haven't got a GH test yet but not sure there would be any practical knowledge from a GH result anyway.

If I could choose fish that like more acid water, avoid ones that like basic water and get lots of plants going it could be that it would work out nicely, you think? The filter will keep ammonia and NO2 at zero, the plants might use a bit of the nitrate being produced and I would do weekly water changes. The plants might like the softer more acid water.

Its either that or decide to use a very small layer of crushed coral (and I like your bit about maintaining it monkey_biz.) And then measure and try to keep that higher pH steady over the years, which sounds like more work.

~~waterdrop~~

 

[monkey_biz]

Coral rubble, crushed coral, limestone, shells, shell grit and coral sand are all calcium carbonate. They all work in the same way.
Lots of people have a section in their canister filter with shell or coral rubble and this helps stabilise the PH and increase the hardness a bit. Other people use pieces of limestone rock as ornaments in the tank. It does the same thing.
Over time the limestone, shell, coral, etc dissolve as they neutralise the acids in the water. This means over the course of a year or two the amount of limestone, shell, etc will be reduced and eventually you will have to add more to keep the PH and hardness up.

just out of interest what is your prefered method. rock based or bicarb?

 

[Colin_T]

just out of interest what is your prefered method. rock based or bicarb?

I prefer to have limestone in the tank. I use it to make up caves and for decoration.
It takes a bit of time to work it out but it's just a matter of adding a piece and testing over the course of a week. Then add another piece if needed. Once you work out how much you need in the tank the PH stays put.

If I am raising the PH of tap water before it goes in the tank, then I use bicarb.

 

[waterdrop]

just out of interest what is your prefered method. rock based or bicarb?

I prefer to have limestone in the tank. I use it to make up caves and for decoration.
It takes a bit of time to work it out but it's just a matter of adding a piece and testing over the course of a week. Then add another piece if needed. Once you work out how much you need in the tank the PH stays put.

If I am raising the PH of tap water before it goes in the tank, then I use bicarb.

Have you a little chart of how much bicarb to use to achieve a certain rise in pH when you use it that way?

 

[Colin_T]

If I am raising the PH of tap water before it goes in the tank, then I use bicarb.

Have you a little chart of how much bicarb to use to achieve a certain rise in pH when you use it that way?

nope sorry. I use a salt shaker for it and just sprinkle some in. Leave it to aerate for 10-15minutes and add some more if needed.

 

[waterdrop]

If I am raising the PH of tap water before it goes in the tank, then I use bicarb.

Have you a little chart of how much bicarb to use to achieve a certain rise in pH when you use it that way?

nope sorry. I use a salt shaker for it and just sprinkle some in. Leave it to aerate for 10-15minutes and add some more if needed.

After the 10-15min you do a KH test?

 

[Colin_T]

nope just a PH test, I don't bother about KH.

 

[waterdrop]

Wait (I'm probably losing the thread of thought as this is drawn out), aren't you using the term "bicarb" to mean Sodium Bicarobonate (aka baking soda) and isn't that supposed to just raise KH and not raise pH (at least not when you don't use too much)? So I don't understand salt shakering in a little bicarb and then measuring to see if you've changed pH (?).

~~waterdrop~~

 

[Colin_T]

yep bicarb is sodium bicarbonate and is used to raise the PH of the water. It also raises the KH.
Depending on how high the pH is the bicarb may or may not raise it much more. If your PH is really high then the bicarb won't change the pH at all but it will increase the carbonate hardness of the water.

You also get calcium carbonate, calcium bicarbonate, calcium hydroxide, sodium hydroxide and a bunch of other things that can raise PH or KH or both.

 

[waterdrop]

yep bicarb is sodium bicarbonate and is used to raise the PH of the water. It also raises the KH.
Depending on how high the pH is the bicarb may or may not raise it much more. If your PH is really high then the bicarb won't change the pH at all but it will increase the carbonate hardness of the water.

ok, teach me something here. My single bit of observation is that I can take my 28G, refill from a 100% water change and add 2 teaspoons of bicarb and my tap pH of 7.5-7.6 will then stay at 7.5 as measured right after the refill and then retain that 7.5 for at least a week. My KH coming in from the tap is between 0-1KH, I think some ppm figure just under 1 degree. So for my one little observation (of KH=1,pH=7.5) the bicarb seems to be following the rule of raising KH but not raising pH. I'm picturing that you must have some mental construct (a table or algorithm) of a changing behaviour of KH&pH when bicarb is added to water with different KH and pH values (ie. this is probably somehow wrong, but picturing an entire table of KH by pH results for a given amt bicarb added to a given KH & pH start point, pictured visually kind of like those CO2 tables we see when talking about adding co2 to a tank - sorry to be so unscientific guess I still can't picture the relationship.)

You also get calcium carbonate, calcium bicarbonate, calcium hydroxide, sodium hydroxide and a bunch of other things that can raise PH or KH or both.

Here you're saying these are other things used to raise ph/kh, right?.. -not- that these are resulting leftovers from using bicarb.

 

[Colin_T]

Hi Waterdrop

Phew that's a load to get around. Not scientific you say. Sounds almost like something you would hear from a lecturer or lawyer
1degree of carbonate hardness on the German scale is equal to 17.9ppm (most people use 20ppm for ease of calculations).
I will leave the KH, PH relationship chart for you to do as homework

Re: "You also get calcium carbonate, calcium bicarbonate, calcium hydroxide, sodium hydroxide and a bunch of other things that can raise PH or KH or both".
They are different chemicals/ minerals that can change the PH or KH but are not related to the use of sodium bicarb, and are not byproducts of the bicarb. They are simply different things that do a similar job to the bicarb.

The only thing I can think of that would cause your tap water PH to remain stable after bicarb was added would be if the tap water actually had an artificially high PH which dropped after the water came out of the tap. Then when the bicarb was added it went back up.

When water is under pressure and in the pipes for a long time it can change a little bit. The dissolved gases can get squeezed out of the water. When the water is put into a bucket and allowed to aerate, oxygen (O2), carbon dioxide (CO2) & nitrogen gas (N) can get back into the water. At the same time the chlorine comes out.
The dissolved gases that go back in to water might drop the PH a bit depending on how much CO2 there is compared to O2 and N. Alternatively once the chlorine is removed the PH drops. This is due to chlorine being highly alkaline.
It's unlikely but the small amount of chlorine in the water could be pushing the PH up and when it is removed and when the water is allowed to absorb normal atmospheric gases, the PH drops a bit.

It also depends on how much bicarb you use in a certain volume of water. 1 level teaspoon of bicarb in 1 litre of water will raise the PH pretty high (about 9.0 I think). The same amount of bicarb in 100litres of water might not change the pH at all but would add carbonate molecules to the water. Thus raising the carbonate hardness but not significantly influencing the pH.
It's probably just this but could be a combination of all of the above. An easy way to test it would be to get 1 litre of tap water and check the PH & KH immediately after it comes out of the tap. Leave the water to stand for 24 hours and test for PH & KH again.
You could have several containers to test at the same time. One could be the control and be sealed up so no air gets to it. The 2nd would be just water exposed to the air. Another could have water conditioner added, and another could be aerated. You would test all containers at the beginning and 24 hours later. This would tell you if the PH of the tap water was changing after it comes out of the tap.
You could run the same test but add 1 level teaspoon of bicarb to the water and compare the results to the first test.
And if you wanted to throw in another variable you could run the same test on distilled water.

 

[waterdrop]

Oh, thank you for that Colin,

Looking back, I must have tried my 2-teaspoons of bicarb for my 28G/106L based on this web page:

Its some guys personal page that has been referenced a number of times by TFF people and so far, to me, it seems pretty acurate on the few things I've had reason to test or talk to others about. Down under KH he mentions that 1 teaspoon should raise 50L about 4 degrees without raising pH. I guess that's been about dead on for me because my tap KH is almost 1 degree and after I add two (slightly rounded) teaspoons I then measure 5 degrees KH in my 106L.

So I gather you must be salt shakering bicarb into a smaller container of water, thus really adding more bicarb per Litre than I am? If so then this must be why you referred to it as a way to raise pH I'm gathering.

I might take you up on those "gassing out" experiments at some point. Unfortunately right now I'm too focused on getting to the end of my fishless cycle. I'm on Day 54 and in two days I'll be at 8 weeks, getting out there among the slowest cases I've read about. My AOBs can drop ammonia really fast and my NOBs seem to make Nitrate but they can't ever seem to make Nitrates fast enough to drop Nitrite to zero. Even when I've only fed the tank a small 2ppm of ammonia in 24 hours, the Nitrites stay spiked up. Any ideas? Maybe I should start a help thread for myself over in "New to the Hobby?"

~~waterdrop~~
ps. I do live at a campus and attend a lot of lectures probably makes me dull!

 

[monkey_biz]

dont forget that bicarb increases the total ammount of alkalinity of the water as well (TA). keeping the TA about 100 will help buffer the ph and stop it wandering suddenly. but getting to that TA you will find your ph about 7.8 or slightly above but if added a very small ammount of a long period you wont raise the ph to much but slowly increase the TA and Kh of the tank. but seeing as you still have no fish you could dump the tank contents and start again if it went pear shaped.

the more you experiment now the more you will learn about your water and your tank so if something goes wrong when you have fish you will know what to do.

 

[monkey_biz]

forgot to say that you should test your tap water on a regular basis, im lucky as i have a photometer so its accurate to 2 decimal places and log it accordingly. last week my tap ph was 6.8 2 days later it was 5 now its sat at just under 7. so what you record you should add one week might be different the next...... oh the joys

 

[Colin_T]

I agree with monkey_biz about the tap water, it should be checked everytime you do a water change. Mine changes throughout the year. If we get pure dam water it is about 7.6. If they give us pure bore water it is about 5.0. Sometimes we get a mixture and the PH is about 7.0. On rare occassions (I gather when they add too much stuff to the water), our PH goes up to about 9.0.