low pH question

[emeraldeyes]

I have a stock JBJ nanocube that has been up and running since 01/02/04 and is stocked with liverock and a inch of sand (live) from my LFS. It has the following inhabitants:

 

one small true perc

one small ocellaris

three pepermint shrimp

two snails( margarita and turbo)

one blue legged hermit

one button polyp

one condy anemone

 

Up until mid Feb, everything seemed to be fine, I thought pH was around 8.0 testing with drytabs and liquid tests. I then purchased Ca+2 and KH tests, as well as a digital pH meter, that I two-point calibrated. Up until mid Feb I was dosing per label with Kent Marine pro buffer dKH nad Mydor Reef and Marine all in one complex #7.

 

When I did the Ca+2 test and KH test in mid Feb the results were:

Ca+2 = 600 ppm

Kh = above 130 mg/L

pH = 7.9 - 8.0 depending on time of day

 

I realized I had a problem and took the following steps to attempt to remedy it:

1) I took water out and aerated it to see if pH changed, and it did not.

2) I stopped adding all supplements

3) I upped my water changes to 15% twice a week

4) I recalibrated my pH meter

5) I started using Seachem marine buffer two to three times a week

 

Now I have the following values:

pH = 7.9 to 8.0

Ca+2 = 575ppm

KH = 130 mg/L

 

whenever I back off on the Seachem buffer at all the pH seems to bottom out.

 

By the way my ammonia and nitrites are consistently zero, and my nitrates are about ten. Salinity is at 1.022 to 1.023 temp of 78.

 

Any suggestions? And also, why hasn't my calcium and KH dropped off a little more with the water changes and no supplements?

 

I am using RO water by the way.

 

Thank you,

 

Debi

[Reefer_Buddha]

first of all that ca is way too high, im surprised it hasnt precipitated out. You should really check your CA levels with just the salt water mixed before adding any supplements. Some salts have enough CA in them at just the right levels. Your ph could be the result of your house or the room the tank is in not being aerated properly. Hard to say at this point but id wait until your levels are at an acceptable range before doing anything drastic. Just so you know water changes wont effect your ph and your dKH i hope you mean is at 13 and not 130. meq/l should be from 2-4.5 and dkh from 7-12.

[MrConclusion]

For the record, here's the conversion factor:

All of these units are legitimate ways to measure KH

50 ppm (or mg/L) = 1 meq/L = 2.8 dKH.

 

ppm (parts per million) is the same as mg/l (milligrams per liter) because there are a million milligrams (of water) in a liter (of water.)

 

Here's an online converter if you're math-phobic

http://saltyzoo.com/SaltyCalcs/AlkConv.php

 

Since I think in dKH, your current 130 mg/l = 7.28 dKH

This is borderline too low. With CA as high as yours, you need more KH to balance it and result in the correct pH.

 

Acceptable range for KH is:

7 - 13 dKH (German Degrees of Carbonate Hardness), or

2.5 - 4.6 meq/l (Milliequivalents per liter), or

125 - 230 ppm or mg/l (Parts Per Million or Milligrams Per Liter)

You should be shooting for the high end with CA like yours.

 

Whether or not you decide to do some large % water changes, I wouldn't worry about the pH right now. It will correct itself as the CA and KH levels come together. For now, at least continue to dose a good hardness buffer. Test the KH right before you add buffer. Eventually you will learn how much buffer your tank is using up, and can cut back on the testing. But always try to test at least every week or two, because tanks needs change with time.

[emeraldeyes]

Thanks for the input. Two additional pieces of info

 

1) When I realized in mid Feb I had a low pH and high Ca+2 I dropped an airstone in the last chamber in the back of the cube, it is still there now.

 

2) yes, I was giving you the KH in the ppm or mg/L unit of measurement - sorry if it caused confusion, but it is 130 mg/L or ppm.

 

Debi