Sudden Drops In Ph, Water Stats Are Mostly Good

[squeakytoy]

Hey everyone... Well, it turns out that Buttercup just had a case of LFS blues... no parasites seen. Yeah! She has put on a little weight, looking a little rounder these days, but I came down three days ago and found her head first in the gravel, looking for all the world like a plane crash! I Reached my hand in to free her, and as soon as I touched the rock, she shot away and hid under the filter intake. Now, being the experienced aquarist I am, I said to myself "hmmm, this might mean something is wrong!" I checked the water, and the ammonia and the nitrites were both zero, but the nitrates were very high, and the ph had dropped to like 6.4 ( usual is around 7.2)! I pulled a water change with a light gravel vac, and things seemed to go back to normal. I checkd them again just now, and my ph is back down to about 6.2 ! So now I am concerned.

water stats are as follows...
5.5 gal
penguin 200 with carbon and biowheel
ehiem 2224 with ceramic rings coarse floss, bio stone and bio ceramic rings

0 ammonia
0 nitrite
20 nitrate
+/_75 hardness (GH)
0 chlorine
40 alkalinity (KH)
6.2 PH


the tank has java moss and spangle (mini lily pad /clover looking stuff) as well as 2 ghost shrimp. One boat ornament and river gravel for the substrate. Any help would be more than welcome, as I am kinda stumped and not exactly clear when it comes to the hard science of water quality and how they are related.

is there such a thing as overfiltration?

 

[drobbyb]

Your KH is a bit low. Low KH can cause a horrible pH crash. I have this problem as my tap water comes out at 6.6 pH and <1 degree KH and GH. If I don't buffer the water my pH will crash fast. Perfect for Discus though. The local reservoir is located in a granite valley with vegetation thus very low buffering capacity as the decaying plant material softens the water.

To fix this I filter through crushed coral bringing my KH to 4 degrees and my GH to 9 degrees and a pH of 7.6.

 

[squeakytoy]

As it happens, I have three bags of argonnite (sp?)... should I put some of that in a filter cartridge or in the cannister? Also, how would you control the amount of buffering taking place. I have only been keeping fish for about a year, and while I can usually puzzle out the mechanical side, the chemistry aspect is still a bit of black magic... I know the basics of cycling, but once you get fancy, I get slower. and I haven't had the time to read up enough on the finer aspects. So far I have been sticking to straight freshwater for exactly that reason too!

 

[drobbyb]

As it happens, I have three bags of argonnite (sp?)... should I put some of that in a filter cartridge or in the cannister? Also, how would you control the amount of buffering taking place. I have only been keeping fish for about a year, and while I can usually puzzle out the mechanical side, the chemistry aspect is still a bit of black magic... I know the basics of cycling, but once you get fancy, I get slower. and I haven't had the time to read up enough on the finer aspects. So far I have been sticking to straight freshwater for exactly that reason too!

You can't control the buffering capacity like this. It's best to test. As a general rule aragonite (crushed coral too) will raise your pH 1 full point with diminishing returns above 7.5. In other words it can only buffer to a specific point. I have crushed coral in my canister inside a nylon bag just under the intake tube outlet with a sponge to prefilter so the coral dosen't get clogged. For me this works perfectly.

I have been keeping fish since I was 15. That was 16 years ago. I don't know everything and probably never will but I like to help where I can and make suggestions. I could do saltwater fish or a coral tank but I prefer freshwater (firstly because salt is EXPENSIVE). Hope that helps!!

 

[squeakytoy]

As a general rule aragonite (crushed coral too) will raise your pH 1 full point

Is there are relationship between quantity of aragonite to water volume for the amount of change required? As it stands, I could use almost a full point up as it is down around 6.2-6.4.

6.6 pH and <1 degree KH and GH

So what is the degree relationship between the two? Sorry if it's a newb question, but... I'm a newb! Only been doing this about a year and a half.

 

[drobbyb]

As a general rule aragonite (crushed coral too) will raise your pH 1 full point

Is there are relationship between quantity of aragonite to water volume for the amount of change required? As it stands, I could use almost a full point up as it is down around 6.2-6.4.

6.6 pH and <1 degree KH and GH

So what is the degree relationship between the two? Sorry if it's a newb question, but... I'm a newb! Only been doing this about a year and a half.

There is a correlation between the amount to gallons of water in the terms of buffering capacity. I can't say exactly how much you need. If you put it into your filter you will experience more buffering as it's not just sitting on the bottom, but being actively filtered through (plus as a bonus crushed coral has TONS of places for nitrifying bacteria!)

KH and GH go hand in hand. They work together to buffer your water. It is possible however to have a high GH and low KH in the case of coral reef tanks as the corals take calcium out of the water.

In my case, my water is too pure for the fish I keep and I have to add. You can also add calcium carbonate and magnesium sulfate to buffer your water. Here is a link for a website that calculates the amount needed in measures: [URL="http/dataguru.org/misc/aquarium/calKH.asp"]http/dataguru.org/misc/aquarium/calKH.asp[/URL]

 

[squeakytoy]

So, I guess higher gh will mean higher kh. generally speaking... Also, gh= general hardness? kh = calcium content? Also, is salinity reflected in any of these?

 

[drobbyb]

So, I guess higher gh will mean higher kh. generally speaking... Also, gh= general hardness? kh = calcium content? Also, is salinity reflected in any of these?

KH = carbonate hardness Salinity is the measure of dissolved salts in the water IIRC