Tropic Marin; High Alk??

R

Rook

New member
Randy,

I recently purchased some Tropic Marin salt and planned to switch from my current Crystal Seas salt to this salt. I tested a fresh batch of Tropic Marin salt that I mixed up and let sit with a powerhead for roughly 18 hours. This is the measurements I got:

Salinty: 1.025
Alklinity: 16+ DKH :eek:
Calcium: 330 ppm
Magnessium: 1150 ppm
Temp is cold, unheated if this matters.

So, you can see my problem. Is this salt with such a high DKH going to be a problem when I do water changes with it?? Is there any way to lower the DKH in the freshly mixed water? Also, I planned to add a bit of calcium and magnessium to the salt to bring it in line, but I'm afraid any added calcium would just precipatate out.

BTW, my current tank parameters as of this morning are:

Salinty 1.025
Alklinity: 9.0 DKH, 3.2 meg/L
Calcium: 415 ppm
Magnessium: 1310 ppm
pH: 8.0
Temp: 80 - 82

Thanks.
 
I've never used Tropic Marin salt, but I've not heard of it having such a low calcium and high alkalinity. Perhaps it is a bad batch, or a testing error of some sort.

Anyone else experience this as well?
 
Perhaps its a testing error, however all tested the alk three times with a Salifert test kit. The calcium I tested with the Salifert Strontium test kit, as my calcium kit just ran out. There could be some error on the calcium.

However, if we assume the tests are accurate, will it cause a problem??
 
It will push down calcium in the aquarium. Before doing anything, I'd get a real number for the alkalinity by using a second syringe of titrant and see how high it really is. Just add the two syringe values together. :)
 
The Plot Thickens!!

Okay, new test results as of tonight.

Tank parameters.

Salinty 1.025
Alklinity: 9.3 DKH, (up from 9.0)
Calcium: 415 ppm
Magnessium: 1320 ppm (up from 1310)
pH: 8.0
Temp: 80 - 82

Since my last test on 1.28.06 I've added 4-5 gallons of limewater on a slow drip and one cup of your magnessium receipe for limewater users with a 9:1 ration of MgCl2 : MgSO4.

The parameters of a fresh batch of Tropic Marin salt, testing two seperate five gallon buckets of salt to ensure there wasn't some residue in one bucket.

Salinty: 1.025
Alklinity: 27 DKH (I added a second titration tube & added the two)
Calcium: 360 ppm (up from 330)
Magnessium: 1150 ppm

The calcium difference, I trust this test more, but keep in mind I am using the Salifert Strontium test kit, which is difficult to distinguish the color change with.

So, the Alklinity is pretty bad, right? But, here is the Plot Twist:

RODI water:

Alklinity 18 DKH :confused:

Given that the alklinity of the RODI is 18, and the freshly mixed Tropic Marin is 27, does that mean the alklinity of the Tropic Marin Salt is 9 DKH ?? Which would be ideal.

So, what's up? I have well water and a water softener. So, either the water itself or the water softener salt contains high levels of Alklinity. I do run the water through an RODI unit and a good one, but it is not working very well right now with the ice cold Michigan well water.

Thoughts ideas?? At least my Alklinity has not raised too much since my last test, 0.3 DKH. And that is after adding five gallons of limewater.
 
Given that the alklinity of the RODI is 18, and the freshly mixed Tropic Marin is 27, does that mean the alklinity of the Tropic Marin Salt is 9 DKH ?? Which would be ideal.

Yes.

The DI of the RO/DI is likely shot (or there is a kit error). Can you measure the conductivity/TDS of the RO/DI effluent?
 
Yes, but its very high. Last time I checked, higher than the incoming water, which did not make sense to me. 250+ I was assuming the TDS was wrong, or something was screwy due to the icecold water and the fact that my 75 gallon per day RODI makes about 5 gallons per day right now.

And, "kit error" do you mean test kit? I am going to take my water for testsing this weekend, but I suspect it is right since the tank water appears to test right. If it was testing high I would suspect it would test everything that high.
 
And, "kit error" do you mean test kit?

Yes, a malfunction in the alkalinity test kit, or user error.

Last time I checked, higher than the incoming water, which did not make sense to me.

How much higher? That can happen in some situations where part of the mixed bed is depleted, but not all of it. The pH of the effluent would be high then. I discuss that in this article:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

specifically here:

http://www.reefkeeping.com/issues/2005-05/rhf/index.php#7
 
Hmmm,

So you are saying that the DI resin may be leaching bicarbonates back into the water, thus having a higher TDS and thus causing the high alklinity?

Strange though, this DI cartridge is only about four or five months old, and I use approximately 20 gallons per week on average. All the other filters were also replaced at the same time. I use a 5 micron - 1 micron - carbon - RO - DI.
 
Well, crud. I guess this means I need to tear apart my RODI unit and figure out what is wrong and why my membrance are apparently being eating up so fast.

Could the cold water, other than causing the RODI unit to work slowly, cause the membranes to degrade faster?
 
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