OK....what gives?

[carmexx]

I have tested my alk/mg/ca over the course of 3 days.

3/15
Mg 1320
CA 350
DKH 5.4 ????? whoa
SG 34 ppt
- dosed 15 ml of Kent DKH buffer

did a 5 gal WC

3/18
Mg 1400
CA 370
DKH 6.3 ??????
SG 34 ppt

Tank is a 46 bowfront, 10 gal sump, SWC 120 skimmer, 2 AI sol blues, sicce return pump (951 GPH) , tunze P/H.
A few acros, BIG toadstool, assorted zoas, gsp, maxima clam 2" maybe (not doing well)
2 Occ clowns, Indigo dottyback, Bi color blenny, and Tiger jawfish
I am using Brightwell Aquatics Neomarine salt with RODI.
I really never had this low of readings of dkh before i started using this salt.....I like that the MG and CA is always right on.

Help

 

[sicksnoopy71]

I have tested my alk/mg/ca over the course of 3 days.

3/15
Mg 1320
CA 350
DKH 5.4 ????? whoa
SG 34 ppt
- dosed 15 ml of Kent DKH buffer

did a 5 gal WC

3/18
Mg 1400
CA 370
DKH 6.3 ??????
SG 34 ppt

Tank is a 46 bowfront, 10 gal sump, SWC 120 skimmer, 2 AI sol blues, sicce return pump (951 GPH) , tunze P/H.
A few acros, BIG toadstool, assorted zoas, gsp, maxima clam 2" maybe (not doing well)
2 Occ clowns, Indigo dottyback, Bi color blenny, and Tiger jawfish
I am using Brightwell Aquatics Neomarine salt with RODI.
I really never had this low of readings of dkh before i started using this salt.....I like that the MG and CA is always right on.

Help

 

[sicksnoopy71]

:willis:I believe what is happening to you is you are restricting your tank from the dentrification process. There can be several things that you are doing wrong here. First off, what temperature does your tank stay at? Are you sure that it does not fluctuate? What is your filtration system like? Need specifics? Water flow, Oxygen? All these factors will affect your Alkalinity readings. How often do you clean your carbon if you use any at all. Dentrification is the last stage of biological process, if you are only allowing your process to go half way you can get low readings of alkalinity. The dentrification process produces alkalinity and thus a more stable ph. Study up change some things and let me know what your readings are. Maybe we can further help you.

 

[carmexx]

just a pic for reference

Temp stays between 78.1 and 78.9 f. Going into the sump i use a filter sock, use no carbon. The flow in the tank is about 1100 gph per tunze 6045 directed at waterline and the return pump is about 900 gph.....I did recently start using a glass top b/c of jumpers.

 

[carmexx]

bump....any ideas? should i start to dose baking soda to raise KH? Change Salt?

 

[DaveK]

First, look at your livestock. If your fish, corals and everything else is doing well, don't try to make any drastic changes. Just about the worst thing you can do is to chase a number by using additives.

Note that after your 5 gal water change, you got better readings, but you only changed about 15% of your water. This is figuring that you sump isn't full and the tank has a typical amount of live rock.

I would continue to make water changes, possibly changing about 10 gal of water, every few days, and see where that takes you.

One think you will find is that different brands of salt mix to different readings. My thoughts on this are that, unless you really know what your doing, you are generally better off just accepting the differences, rather than playing "kitchen chemist" and using additives to chase a number. Of course there are some bad brands of salt out there that mix way off, and in these cases, you want to change your salt brand.

 

[carmexx]

Thanks Dave. I was reading up on DKH and i found out that NSW is around 7 or 2.5 meq/l. the article also referred to the fact that most Aquarists try to hit the 9 mark for some wiggle room. Well i did some more tests today.

3/22 Pre water change

SG- 34
PH 8.1
DKH 7 / 2.5 meq/l
CA 340
MG 1300
Temp 77.9

My livestock seem to be happy....Polyp extension on sps and softies, although clam didn't make it. I did in the last few days ad 15 ml of DKH buffer per day so maybe that helped.

 

[carmexx]

I am back! After keeping a close eye on things I finally tested my new makeup water. It was as follows:
sg 34ppt
dkh 7 or 2.5 mg/l
mg 1500
ca 500

I am using brightwell neo marine salt. I suppose I should accept the dkh around 7 and not "chase" a number as suggested.

 

[DaveK]

Here are a couple of good articles on this whole issue (offsite) -
http://www.advancedaquarist.com/2002/11/chemistry
http://www.advancedaquarist.com/2003/10/chemistry
http://www.reefkeeping.com/issues/2006-06/rhf/

You may have already seen some of them. One thing to keep in mind. These articles are by Randy Holmes-Farley, so they tend to get very deep into the subject. Most reef keepers are often more interested in just fixing their problem, rather than all the chemistry behind everything.

Another factor is the salt and how it's manufactured. There are several ways to get from "point A to point B" as far as what different salts go into the mix. Ever notice how some salts dissolve clear and others leave some precipitate behind, even though your using the same RO/DI water? Also, different brands will usually mix to different levels of calcium, alkalinity, magnesium and pH. Also, you might see salt from the same manufacturer vary, in other words, it's not as consistent as it could be.

This is why I usually recommend water changes first, and the testing of the newly mixed SW. It's also why I tell people to first consider how your livestock is doing before you start to mess with things.

As a note, some reef keepers will go to great lengths to get the number "right on". For example, alternate between brands of salt for water changes because brand A is high in calcium and low in alkalinity and brand B is high in alkalinity and low in calcium. Others will mix a batch of SW and then use additives to get to the levels they want. I'm of the opinion that either method is a mistake. My preference is to find a salt that gives you the levels you want when you mix it, and stick to it.

 

[ddelozier]

+1 DaveK. Chasing numbers will leave you frustrated. If you livestock is doing well, dont chase numbers. I use Instant Ocean and even their Reef Crystals when they are cheap