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Okayamapiper
10/03/2009, 01:47 AM
Hello. I have a 40 gallon tank. Parameters are
Temp 25C
No2 zero
No3 5ppm
PO4 immeasurable
Ca 420
dKh falling
Mg 2400ppm

I am using Randy's bi-onic solution but previous used Kalk and vinegar. My Mag was not monitored and went through the roof. I noticed a problem with dKh going from 12 down to 7 in 24 hour period. Also there is a white precipitate forming in the sump after starting the bi-onic solution. Is that Calcium carbonate or Magnesium Carbonate. I cannot find any literature on what happens when Mag gets this high. I have done two 50% water changes and got it down to 2400 and will probably do a couple of more once I get some more salt. Any ideas on the identity of the precipitate and whether the Mag is causing the ALK to plummet?
Regards,

James

Randy Holmes-Farley
10/03/2009, 05:25 AM
You're into uncharted territory with magnesium that high, but it might be magnesium hydroxide or carbonate.

Have you measured pH?

Randy Holmes-Farley
10/03/2009, 05:40 AM
FWIW, I discuss such precipitates here:

What is that Precipitate in My Reef Aquarium?
http://reefkeeping.com/issues/2005-07/rhf/index.php

Okayamapiper
10/03/2009, 07:15 AM
Randy,

I'm a big fan of yours and have read your site. The white precipitate is a mystery. As for pH I am awaiting arrival of a test kit as my reagent has gone dry.... I just went through two 60 liter water changes today in a 160 liter system and have scrounged up enough salt for one more for tomorrow. Hopefully this will get my Mag under 2000ppm. Could the high magnesium account for the dKh dropping every day after using your bi-onic solutions? I will try to get pH data to you tomorrow. BTW there is probably some extra calcium coming from the sulfur denitrator which might be making the two part additive go out of whack. Too many variables here I guess....

Regards,

James

Billybeau1
10/03/2009, 07:25 AM
Okay, first

[welcome]

Many times we have test kit issues. I'm wondering first off what brand test kit you are using to measure magnesium ?

Magnesium hardly ever gets that high unless you are supplementing huge amounts of mag sup. And I mean huge.

You may have other issues so lets deal with them one at a time.

What salt mix are you using for your water changes ?

Randy Holmes-Farley
10/03/2009, 07:50 AM
Could the high magnesium account for the dKh dropping every day after using your bi-onic solutions?

Whatever the precipitate is, it almost certainly is reducing alkalinity, or at least preventing it from being added properly, since it is likely some sort of carbonate or possibly magnesium hydroxide.

Okayamapiper
10/04/2009, 01:48 AM
The test kit is a Sera (German kit) and was purchased 4 months ago and the lot number is new so I assume it is okay. As for the source of Magnesium, I used Kalk with vinegar for a couple of years so the Magnesium that would settle out if I had allowed it to would never have gotten into the tank. That plus some Epson salts are probably the cause. Irresponsible dosing in a puny tank was the cause.

As for pH it is 8 or 8.1. dKH was 6 this morning. I will change out 33% of the water today. A series of 4 such water changes with an initial 2400ppm and new water with 1200ppm should put me down in the 1400ppm area in the end.

As the precipitate is in the bottom of the sump should I remove it just in case it is magnesium and could go back into solution in the future?

Regards,

James

Okayamapiper
10/04/2009, 01:51 AM
As for the salt mix I use Instant Ocean usually and Salt Square (made in Osaka) when I am in a pinch. Also as I acquire about 60% of my livestock and coral from the local sea, I use natural sea water whenever I remeber to take my jugs.

Cheers,

James

Okayamapiper
10/04/2009, 02:29 AM
So far I have done 4 water changes ( three 50% changes and one 25% change ). Assuming that initially I had something ridiculous like 5000ppm, the series of changes should have left me with 1516ppm, assuming that the salt mix only contained 1200ppm of magnesium. Even so, my test kit shows nothing even close to this, would it be safe to assume that the Sera kit is off? I will try adding the bi-onic to see if dKH is stable and test both pH and dKH in the morning.

Cheers,

James

Billybeau1
10/04/2009, 05:31 AM
I think it is safe to say your test kit is bad or you are not using it properly.

The only two magnesium test kits I trust are Salifert and Elos.

I doubt there is little, if any, magnesium in kalk so it must be the Epson. Even then you would need huge amounts to get the numbers you are seeing.

Okayamapiper
10/04/2009, 10:07 AM
I agree. The test kit must be trash even with the $22 price tag :mad2: .
The low Alk is probably due to the denitrator effluent. I dripped some Kalk to raise the pH up to 8.2 and the dKH is recovering. I guess the 7.8 pH dentrator effluent was the culprit. I have slowed the denitrator flow to allow the aragonite a chance to raise the pH before it returns to the sump. If worse comes to worse I will continue dripping Kalk. Calcium is hanging around 490, so I guess things are coming around. I thank everyone for their input. :wave:

Cheers,

James

Okayamapiper
10/04/2009, 07:05 PM
Checked pH and dKH this morning. pH was 8.2 and dKH was 9, so things are looking up. Again thank you.