Help! I need some suggestions to fix my dKH levels

[Ruth]

The first thing that jumps out at me is that your magnesium levels are low. I would try and get that up to 1350 - 1400 (over time of course but you already know that). That could very well be what is causing your other levels to be out of whack.
If it were me I think I would be just tempted to stop dosing Kalk altogether for a while - stop adding any kind of buffer and just do larger water changes - like maybe 40% every 4 or 5 days and see if this does not bring everything back into balance. Is there any chance that you got a bad bucket of salt? Have you tried to measure what levels your fresh mixed change water is?

[michika]

The salt I use naturally has low dKH, I should have mentioned that. I'm not really open to changing my salt brand just because I have a full bucket right now.

I actually have been dosing Mg regularly as well (8 hours apart from the alk.), and its barely doing anything. I do have 2 mangrove plants in my sump, and I know they take up quite of Mg. You can see the rise in Mg the day after I dose.

I do 5g water changes ever week, and lately (in the last two weeks) have bumped it to 10g. Again because of the low dKH levels in my salt I feel its contributing to the problem.

These are the levels I got from freshly mixed up saltwater with RO/DI:

Red Sea Coral Pro Salt
SG 1.025
Mg 900
Ca 460-480ppm
dKH 6 or 2.2-2.6 meq/L

I'm afraid to stop dosing dKH for fear of it dropping below 4. What do you think would happen if I stop dosing? Would the levels continue to drop? I wouldn't mind stopping dosing, actually it would probably nice to do one less thing each day.

So if I understand, your recommendation is to work on raising my Mg levels, and in the mean time to stop dosing alk.

[ClubReef]

Hi Katherine,

I remember reading Randy Holmes-Farley's article on the relationship of Calcium and Alk...

In the section labelled "Apparent Excess Demand for Alkalinity" he says,

"If an aquarist is supplying a balanced additive to his aquarium, and calcium seems stable but alkalinity is declining, it may very well be that what is needed is more of the balanced additive, not just alkalinity. "

Perhaps your tweaking with the buffer is becoming counter-productive. Try doing some water changes and get back on a balance dosing schedule..or if you are on a reactor..try adjusting the dosage.

You can read his article here:
http://www.reefkeeping.com/issues/2004-12/rhf/index.php

Hth

[danny zubot]

Perhaps your ALK additive is defective. Have you tested it? Have you ever tried to use the 2 part home made additive?

[michika]

I'm using Seachem's Carbonate product in liquid form. It does work, its just not having a staying power. There is a upward movement in dKH after dosing, I just can't get the levels high enough, or get them to stay. I also tested just the product in freshwaster (before dosing), and it gives me a high dKH reading. I assume that means my product is okay.

I think I also need to do something about the fact that the salt I'm using starts out with low dKH. How do I address this?

I have tried using Baking Soda in the past, granted it was on a larger system, and I had to dose continually with it as well. At that time I was using a different salt brand.

So to sum up the suggestions so far:
- stop dosing to raise dKH, and instead focus on raising my Mg levels.
- look into if my additive is defective. Done.
- change the dosage in my reactor. Does this mean change the drip rate, or the strength of the additive entering the water?

I'm starting to think my problem is that I'm starting with low dKH (thanks to my salt mix), and once that is in my tank a lot of it, and the Ca is being used up because the tank is filled with SPS, and clams.

I guess the question is now how is the best way to raise and keep my dKH at appropriate levels? A reactor? A dosing pump?

[Ruth]

What I would do - I think - is to stop adding anything directly to the tank. I would mix up change water and make sure that the levels in your change water are where you want them to be - so in other words add the "stuff" to your change water. Let the water sit for a couple of days to make sure it is going to maintain the appropriate levels - then do water changes. I would be worried that with all the additions to your tank you are actually damaging the balance and causing fluctuations. IMO it is not the corals and clams that are sucking the calcium out too fast. In my 110g cube I only dose with C-balance and do weekly 20% water changes. It is filled with SPS coral and 5 large clams (6-8"). I am using Tropic Marin salt on this tank.
If your salt is what is causing you the problem with this tank it might be cheaper to change salt now and lose $50 (or however much it is) than lose your corals and clams which are probably worth a fair bit more. Besides someone with a softies or FOWLR tank might want to buy your unused salt.

[reeferaddict]

I couldn't agree more with Ruth here. If your livestock is showing no signs of distress, I would do it this way until all your levels are where you want them. My system uses controlled evaporation to adjust the amount of Kalk I dose daily, but eventually it ends up Magnesium deficient like yours, and Calcium and Alk are hard to maintain once your Magnesium goes under 1000pm.

I would liken it to pouring your Ca+ and Alk supplements down a drain if they are precipitating to where Mag is supposed to be. The Randy Holmes Farley article posted is about as explanatory as it gets too... I would do water changes with extra Mag in the water and once these levels get back up to 1250 - 1300 ppm I am almost certain your Alk and Ca problems will go away.

One other thing - getting your S.G. up to 1.025 from where you are at should take your Calcium concentration up around 20ppm due to the extra dissolved salts in the water. Your dKH may be a little higher because of this as well.

As for making your water the right levels... I use Kent Osmo-Prep Marine with my RO/DI water and Instant Ocean salt. After mixing, Calcium is right around 400ppm and Alk is at 8-9 dKH. Maybe try this before you change salts?