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Awesome response from seachem. My only question is that they talk about CO2 as being the culprit, if we aerated the water while it was mixing, wouldn't this eliminate the problem? I'll have to do some research to find out why, but I assume the fact that letting your salt mix for a minimum of 24 hours is a well known standard came about for some good reason.

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Awesome response from seachem. My only question is that they talk about CO2 as being the culprit, if we aerated the water while it was mixing, wouldn't this eliminate the problem? I'll have to do some research to find out why, but I assume the fact that letting your salt mix for a minimum of 24 hours is a well known standard came about for some good reason.

CO2 will always be an issue. Chemically speaking what happens is that CO2 in the water column (which is always present in varying amounts) causes the water to become acidic (ph) and in the natural processes that take place Alk will begin to be effected. No matter what salt you use there will be a drop weather you buffer or not. You would need to buffer/add alk virtually everyday in order for your alk not to drop. Aeration helps but you will never eliminate the CO2. Gas exchange is an important factor in our tanks/makeup water which help balance out the oxygen, nitrogen, carbon-dioxide, etc in our tank, but this is a never ending cycle. Most people use this 24 hr +/- mixing time frame to let the everything balance out. The salt mix is not alwasy in perfect ratios of Alk:Ca:Mg in every scoop by letting it mix over a time period these natural processes take place allowing the mix to stablize which usually means some precipitaion (less for good salts) then you usually end up with a balanced saltwater mix after this time period. Sorry about the book, not sure if this is helpful or not.

ocean-chemistry.gif

Edited by chegman

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Nice! Now this thread is starting to get somewhere. After reading what seachem had to say I'm going to try and change when and how much salt I mix up. I've been mixing up salt in large enough amounts to last through about four days of water changes. (Been doing WC at least every other day trying to control a NO3 issue)

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More from Seachem this morning:

Hello Wade,

You may be over-mixing the salt. Our salinity is very different. While other salts take a good bit of mixing, it is preferable to not mix ours too much. Here we only mix it for several hours before using it. We also use a small power head in a 50 gallon drum. Your large pump may be introducing too much CO2 and along with the over-mixing both can cause precipitation of alkalinity. Perhaps next time you mix salt you can shorten the mixing time and use a smaller pump. I hope this information helps.

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So with this new knowledge in hand I made up a batch of fresh salt water last night. Here are my numbers:

Salinity 1.026

Alk/KH 3.77/10.6

Mag 1380

Cal 450

This after about 4 hours of mixing. Turned the pump off every so often so as not to over oxygenate the water.

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Those are nice numbers pretty close to my tank numbers I might be switching salt?!!? I like that you only mixed for a short period and got these numbers. Like I said before my salt runs higher in all the listed elements, but it doesn't make much sense if I am running lower in my tank. I am interested in seeing, after you do some water changes with this new knowledge how your tank parameters matchup over time, I know it will not be to accurate of a reading cause you probably dose, but still could be interesting if you notice a difference.

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So after reading this post I tested my water from the tank and the RO water.

We use Corallife salt

The Tank water

pH - 8.1

Ammonia - 0

Nitrates - 20ppm

Salinity - 1.023

Calcium - 500

Alk - 215ppm / 12.04dkh

I also tested the RO water for pH which was way below the chart under 7.4, the test tube was yellow. Once I mixed the salt with the RO water the pH came up to 8.2. Knowing the pH in the RO water is way low should I buffer the RO water I use to replace water that is evaporated?

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So after reading this post I tested my water from the tank and the RO water.

We use Corallife salt

The Tank water

pH - 8.1

Ammonia - 0

Nitrates - 20ppm

Salinity - 1.023

Calcium - 500

Alk - 215ppm / 12.04dkh

I also tested the RO water for pH which was way below the chart under 7.4, the test tube was yellow. Once I mixed the salt with the RO water the pH came up to 8.2. Knowing the pH in the RO water is way low should I buffer the RO water I use to replace water that is evaporated?

No. It will be so quickly diluted nothing will ever notice and your water will just remain as it should

Sent from my DROIDX using Tapatalk 2

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I also tested the RO water for pH which was way below the chart under 7.4, the test tube was yellow. Once I mixed the salt with the RO water the pH came up to 8.2. Knowing the pH in the RO water is way low should I buffer the RO water I use to replace water that is evaporated?

No. It will be so quickly diluted nothing will ever notice and your water will just remain as it should

Sent from my DROIDX using Tapatalk 2

I actually disagree, many people buffer their top off water, just adding a pinch of buffer to your top off water will bring the pH up, and preserve some of the buffering ability of your salt.

I'm not going to pretend to know anything close to everything about water chemistry, but I did minor in chem in college, and tutored it for a long time. I know it obviously isn't 100%, but I remember learning and teaching people that theoretically the only thing that should effect the pH of a solution is the concentration of buffer in solution (at STP of course). There are obviously other factors that play into the pH equation (CO2, not being at STP, a variety of other things), but the way I see it is, why purposefully reduce the concentration of buffer in your tank, if you could just add a small amount to your top off water before you add it to your tank. As a final note, for those who don't understand what alkalinity is, it is the buffering capacity of your water, if you're constantly adding unbuffered water to your tank (some people are adding gallons per day), you're using up your alkalinity in order to correct the pH, and hence your alk will drop quickly.

Now if you're dosing alkalinity, then there isn't much of a difference whether you add it to your top off water, or straight to the display. But for those who don't dose, and are just using water changes as a means to replace lost alk, you could see more alk stability if you were to buffer your top off water before adding it to the tank.

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^ +1 before I started dosing I noticed ph changes when I topped off (manually) and would also notice a drop in alk. I now use 1/8 tsp of reef builder 8.3 per gallon of top off water in my ATO. I don't know if it would be better to use soda ash or not but that's an experiment for another day right now.

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Good points, the correction needs to come from somewhere--I dose so I do not buffer my top-up water.

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Like salt, wouldnt the alk and buffering abilities of the water remain still largely in the tank? Evaporation doesnt cause tank ph/alk to rise?

I know its abilities to buffer will be reduced over time for non dosers, but daily top offs should bear minimal effects i would think.

Sent from my DROIDX using Tapatalk 2

Edited by DerekFF

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Derek I think you are right, the effects are minimal but also seem to be cumulative over time. When the devil is in the details and the key is consistency, why not try and add only thing that match your tank chemistry or what your target chemistry is.

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Like salt, wouldnt the alk and buffering abilities of the water remain still largely in the tank? Evaporation doesnt cause tank ph/alk to rise?

I know its abilities to buffer will be reduced over time for non dosers, but daily top offs should bear minimal effects i would think.

Sent from my DROIDX using Tapatalk 2

The effects would depend on each situation. To be honest, I haven't looked at how the units we use for alk relate to the chemical equations, and thus have no way to actually figure out how much of a swing in alk is caused by top offs. But I would say it would depend on your tank, if you're topping off 5 gallons of water a day vs 1/4 gallon per day, you'll see varying degrees of swing.

To me though, it just seems like a very simple way to keep your water even more stable. You will have no localized pH swings, the alk should stay more or less constant, and it should only take you a second to add the buffer to the top off water. When you fill it from your DI, just add some (depends on how big your resevior is) buffer to the resevior and forget about it.

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I'm glad I saw this post I wondered why my alk was always low after a water change. I kept mixing my water for upto a week before I used it.

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New box of Reef Crystals/RODI 0tds

Temp: 78

Sg: 1.025 (refrac)

Alk: 11.76 (Hanna)

Ca: 430 (Elos)

Mg: 1390 (Salifert)

Ph: 8-8.1 (Salifert)

Mix time: 12 hrs

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New bucket of reef crystals 1/27/2013

Temp 78

Mix time 4hours

Salinity 1.26 (refractometer)

Ph 8.2 (API)

Alk 10 (red sea)

Mag 1640 (red sea)

Cal 470 (red sea)

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If you drip your top off water slowly into your tank then the tank water will slowly adjust (slight alk drop, slight drop in salinity cuz you just diluted your tank with pure water).  You can tweak this effect by adding CaOH (kalkwasser) to your make up water so you are adding more base, baked baking soda (sodium carbonate) which will add Alk and slightly raise pH, or half a dozen other ways.

 

Secret to long term stability is to pick one technique, attempt to keep chemistry relatively consistent, and always test before you adjust.

 

For the record, I use a float valve with RO/DI and notice drops of around 0.0005 salinity and constantly tweak my dosing pumps to keep my alk around 9.5 dkh.  I'm currently dosing 8 ml of b-ionic two part four times per day.  I'm using seachem reefsalt cuz the parms are close to what I want to keep my tank.

 

PS I used to use Reef Crystals but find the alk is consistently too high (~11 dkh upon mixing and ~10.5 after 3-4 hours). Slight drop could be explained by pick up of CO2 from the air. Who knows.   In fact, I still have a bucket of it in the garage.

 

PPS Will post numbers from seachem reefsalt after fresh mix then after several hours when I do my water change next weekend.

 

Good thread.

Edited by plankton

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I have been using salinity for a couple years and am getting ready switch brands. This is the last of the bucket so I am not sure if that makes a difference.

This is after 24 hours at 78 degrees.

 

Salinity 1.022

Cal 325

Alk 11

Ph 7.8

 

Not vary pleased with the results.

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I just got a new bucket of microb-lift riff salz. I mixed it up 24 hr ago.

 

Salinity 1.023

Kh 13=6.5

Cal 300

Ph 8.0

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