A Few Ph Gh And Kh Questions...

[Squid]

I have been considering moving to a malawi/mbuna tank, and so I have been doing some testing of my water again to see if it is suitable. I ended up with three different results for the PH. (i have put this in tropical chit chat, as the question is more generally about stats than mbuna)

Result one: My current community tank PH was right down in the 6 direction. Do i take it that this is due to the bogwod that i currently have in the tank? I presume so, so I will be ignoring that result. I will be testing it again after my 25% water change tomorrow.

Result two: I then tested my tap water, and this came back with a PH of pretty much spot on 7.0. This was a little suprising as i remembered it being a little higher.

so then i thought i would test it again.. ensuring i put the right amount of drops in correctly and making sure the bottle was properly vertical etc.

Result three: The result cam back somewhere about 7.5. i thought the varying results were odd, so checked it about 3 more times with normal and High PH tester, and 7.5 it is.

so...

Is this likely to be me doing the test wrong the first time, or would leaving the tap running for a while (which i did whilst testing) make a difference? not sure why? .. or any other variable??

I also bought myself a GH and KH test kit by Nutrafin. The results were GH of 140 mg/L and 120 or 130 mg/L (cant remember now). Whenever i see results posted on here I see much smaller numbers such as 8.

so..

is this the dH and gH figure instead of the GH and KH mg/L.. if so, the kit said that i should multiply the results by 0.056 in order to get these results.. which would make GH = 7.84 and KH of 6.72 or 7.28.

Once i have established im doing all of this right, i can then go off to the Mbuna side to pick their brains on whether my water is desireable, and/or the best way to enhance its desireability with coral-sand etc.. and by the looks of it.. definately no bogwood LOL..

Cheers for your help..
Squid

 

[WILDER]

What test kit are you using.

This might help.
http/www.drhelm.com/aquarium/chemistry.html

 

[Squid]

What test kit are you using.

API Master (the one with PH LOW, PH HIGH, Ammonia, Nitrite and Nitrate) for the PH.. (Liquid)

and the Nutrafin KH/GH one.

Squid

 

[WILDER]

There is a big swing in your tank ph to your tap ph meaning you can't do large water changes.

 

[Squid]

There is a big swing in your tank ph to your tap ph meaning you can't do large water changes.

That would explain why I have had some probles with certain fish, even though the rest of the stats have been fine.

Would you suggest a 10% water change twice a week being preferable to a 25% water change once a week?

Although, if i move across to Mbuna, there will be no bogwood in the tank to cause the large swing in the tank PH i expect. One of the bits is extremely dense, and took about 6 weeks just to reduce the tanins to a reasonable amount.. thats not doing the PH much good then.

Thanks for your quick responses.

Squid

 

[WILDER]

Just remove the bogwood then your ph will match your tap ph.

 

[Squid]

Any other comments as to why the ph was lower in the second test.. and whether the calculation used/ method of measurement for how people represent KH and GH was correct?

 

[Liam]

For the tap water ph and even the tank water ph you get a more accurate result leaving the samples out for 24 to 48 hours, this allows the Co2 to gas off, the tap reading is usually lower than the actual ph of the water mine is over half a point difference. Yeah the .056 is the correct way to get from mg/L to dH.

 

[CFC]

If people are going to answer to scientificly based questions please do so with more than one line answers and divulge a little more information rather than just spouting advice that isnt nessesarily right with no explanations.

It would seem that your water is too soft for African Cichlids which preffer a GH and KH of between 20 and 30, i fear that without constantly supplementing your water with buffers and minerals you would have no end of water chemistry related problems with the fish such as pop eye, bloat and general ill health. The African Cichlid folks can help you more but i expect they will say the same thing.

The pH dropping by 1 degree in the comunity tank needs looking into, you need to measure the KH in the comunity tank and compare it to that of your tapwater, if the level is considerably lower it is an indication that your maintainace needs increasing. The pH scale is logarythmical (spelling?) which means that a change of 1 on the scale is a change of ten times the acidity/alkelinity so its quite a drop. It is likely you need to increase the amount of water you change and clean your filters more regularly to remove dissolved organic solids which release humic acids into the water which dissolve the calcium bicarbonate which buffers the pH.

The advice on letting tapwater sit to release CO2 before testing is sound advice.

 

[andywg]

CO2 usually gasses off quite freely by surface agitation. I would expect one to get a similar effect by putting the sample in the tube and shaking it before opening the top again. Repeating this a couple of times should give very similar results to letting it sit if you are impatient (as am I).

 

[Squid]

If people are going to answer to scientificly based questions please do so with more than one line answers and divulge a little more information rather than just spouting advice that isnt nessesarily right with no explanations.

It would seem that your water is too soft for African Cichlids which preffer a GH and KH of between 20 and 30, i fear that without constantly supplementing your water with buffers and minerals you would have no end of water chemistry related problems with the fish such as pop eye, bloat and general ill health. The African Cichlid folks can help you more but i expect they will say the same thing.

The pH dropping by 1 degree in the comunity tank needs looking into, you need to measure the KH in the comunity tank and compare it to that of your tapwater, if the level is considerably lower it is an indication that your maintainace needs increasing. The pH scale is logarythmical (spelling?) which means that a change of 1 on the scale is a change of ten times the acidity/alkelinity so its quite a drop. It is likely you need to increase the amount of water you change and clean your filters more regularly to remove dissolved organic solids which release humic acids into the water which dissolve the calcium bicarbonate which buffers the pH.

The advice on letting tapwater sit to release CO2 before testing is sound advice.

Thanks for the information CFC & liam (Edit: andy.. i may try that as a comparison after wating.. then i will know better for next time.. thanks)

The pinned topic in the African Cichlid section said that a KH of 8 was desireable, and that people with less than a PH of 7 were not suitable. But if it is the case that it needs to be above 20, then it looks like i have a problem. With mine being a PH of 7.5 and a KH of 6.7 or 7.2 I was hoping that by using Ocean rock and coral sand that it would be enough to bring the stats into line, but if this does not act as a permanent buffer, once again I will be in trouble. I will post the details in the African Cichlid section and see what they say, but I dont want a load of unhealthy fish, so perhaps i need to look at other options for my community tank.

With regards to the community tank and the PH scale, I hadn't realised that it worked like that. I guess that if the tank PH was about 6.1 and the tap PH is 7.5, then a water change of 25% would cause it to change to 6.45 (using (6.1+6.1+6.1+7.5)/4). By the sounds of it even that is a change that is too big. Would you recommend removing the large piece more dense bogwood?

Edit:.. one last thing, would it be advisable to do one or two larger water changes to raise the PH, and then aim to keep it higher than it currently is?

I will leave some tap water sitting around for a day or two and test it.

Many thanks
Squid

 

[CFC]

Sorry my bad there, a KH of 30 would be liquid chalk It should have said a GH of between 20 and 30 and a KH of 8 or above but it looks like my brain was going quicker than my fingers.
You could have a pH of 8 but if your KH is low then the pH is going to drop the moment any organic matter starts to break down and release acids, its the KH that stabilises the pH.
You could raise your KH by adding baking soda to the new water at water changes which will increase the calcium bicarbonate levels, i think the recomended ammount is 1tsp per litre to raise it by 1 dKH, but i'd do some experiments with buckets of water first to find out how much you need.
If you can get the KH up to 8 and the pH stays stable at 7.5 this should hopefully give you a GH of 15.5dGH (KH+pH=GH) which should be just about hard enough for Malawi's provided it stays there.
Please dont take this as gospel though as i dont hold any scientific qualifications, i would check with one of the more scientifically minded members like Lateral Line, Bignose or Nmonks before doing any of this with live fish.

A change of .35 in the pH is fine, its generally not recomended to alter the pH by any more than .50 in each 24 hours.

 

[Squid]

Thanks CFC, sound advice as ever.. I have posted in the African Cichlids section too as advised, so i will see what happens.

Squid

 

[andywg]

A good way to help buffer the KH and the pH is through the use of aragonite sand as a substrate.

 

[Squid]

A good way to help buffer the KH and the pH is through the use of aragonite sand as a substrate.

I seem to remember this chap using that sand, and it was partly his tank that made me want to go in this direction.. http/www.fishforums.net/index.php?showtopic=117623

Is it readily available?

Squid