Could use some advice on my numbers

[crs2k]

Hello everyone,

 

So I've been trying to read as much as I can about the relationship and desired levels of Ca, Alk, and Mg as I feel my numbers are a little strange. My current numbers as of tonight, 6 days after water change(weekly waterchanges every Tuesday with Seachem Reef Salt and RO/DI):

 

Nitrate: 0

Nitrite: 0

Ammonia: 0

PH: 8-8.2

Phosphate: 0

Ca: 480

Alk: 5-6

Mg: 1300

 

I just got a new Elos Mg test kit and this is the first time I've used it. My LFS showed me how, and when he did it with my water, he got 1050. So my number of 1300 is a little different. Not sure why.

 

The other numbers are all coming from API test kits, and my Alk as of late has been consistantly low around 5-6.

 

The tank is a 14G biocube ( you can see in my sig what I have as far as corals), but it's nothing to crazy.

 

So what do I do about my Alk? I heard and have read about a little baking soda, but not sure how much to use and how to dose it. But my PH would drop, right? So where do you think I should start?

 

Thanks so much. Oh yeah, the tank is over a year old.

 

Chris

[disaster999]

i use baking soda to dose my tank and works well. there are recipes online you can use to make your own 2 part solution. the one i use is 297grams of baking soda for 1gal of water. it will lower your ph a little bit, but with your ph is fine.

[Mr. Fosi]

PH: 8-8.2

Ca: 480

Alk: 5-6

Mg: 1300

 

It's good that your pH is in an acceptable range with alk that low. Are you testing after the lights have been on for a while?

 

That alk should be 8-10 dKH but I think you already know that. Your Mg concentration is fine, though I generally try to keep mine around 1350.

 

I just got a new Elos Mg test kit and this is the first time I've used it. My LFS showed me how, and when he did it with my water, he got 1050. So my number of 1300 is a little different. Not sure why.

 

Probably because you over-titrated and shot past the end point without recognizing it. Run the test again and go slower when dripping in the final reagent (an acid) while swirling the vial to make sure that it stays well mixed.

 

If you don't keep the solution mixed as you add the acid or you add it too fast, it is very easy to add too much and end up calculating an artificially high concentration.

 

The other numbers are all coming from API test kits, and my Alk as of late has been consistantly low around 5-6.

 

API generally reads higher than both my Salifert and homemade kits... Sometimes as much as 2 dKH. I would test it with a higher-end kit if possible to see how it compares. Either way, that is much lower than it should be.

 

So what do I do about my Alk? I heard and have read about a little baking soda, but not sure how much to use and how to dose it. But my PH would drop, right? So where do you think I should start?

 

I think you should start by adding some alk.

 

If you read Randy's DIY 2-part article, you'll see that there are two simple ways to add alk:

 

1) baking soda, a.k.a. sodium bicarbonate (NaHCO₃)

2) washing soda, a.k.a. sodium carbonate (Na₂CO₃)

 

NaHCO₃ will lower your pH slightly just after you add it and Na₂CO₃ will raise it.

 

You can easily make Na₂CO₃ from NaHCO₃ by baking in your oven. Spread some baking soda (not too thick) onto a baking sheet or some aluminum foil and bake it in your oven at 350F for 2 hours. This will drive off CO2 and H20, thereby converting all the baking soda (NaHCO₃) into washing soda (Na₂CO₃). You'll see that Randy bakes at a lower temp for less time, but I like to be sure that I get a full conversion of all the reagent. I know that mine works because I have done the weighting and stoichiometry. Randy's probably does too but I like to lean on what I know rather than what I have been told whenever possible.

 

Whether you choose to use baking or washing soda, you will dissolve them into some RO/DI water. Randy's recipe states:

 

Spread baking soda (594 grams or about 2 ¼ cups) on a baking tray and heat in an ordinary oven at 300°F for one hour to drive off water and carbon dioxide. Overheating is not a problem, either with higher temperatures or longer times. Dissolve the residual solid in enough water to make 1 gallon total. This dissolution may require a fair amount of mixing. Warming it speeds dissolution. This solution will contain about 1,900 meq/L of alkalinity (5,300 dKH). I prefer to use baked baking soda rather than washing soda in this recipe as baking soda from a grocery store is always food grade, while washing soda may not have the same purity requirements. Arm & Hammer brand is a fine choice. Be sure to NOT use baking powder. Baking powder is a different material that often has phosphate as a main ingredient.

 

And for baking soda:

 

Dissolve 297 grams of baking soda (about 1 1/8 cups) in enough water to make 1 gallon total. This dissolution may require a fair amount of mixing. Warming it speeds dissolution. This solution will contain about 950 meq/L of alkalinity (2660 dKH). As mentioned earlier, Arm & Hammer is a fine brand of baking soda to use in these recipes. Be sure to NOT use baking powder. Baking powder is a different material that often has phosphate as a main ingredient.

 

Once you make up your solutions, use a reef chemistry calculator to help you determine how much you need to add to bring your numbers to where you want them to be. If you use that calculator I just linked, be sure to tell it that you are using Randy's recipe #1 washing soda or #2 baking soda because the numbers will be very different depending on which you use.

 

I use washing soda (Na₂CO₃) because I don't have to add as much to get the effect I want and I always do my dosing in the morning when my system's pH is low. If I had to dose in the evening when it was high, I would consider using baking soda (NaHCO₃).

[divecj5]

You're the man Fosi....after 3+ years of reefing, I find every one of your posts still helpful and insightful. Must be because you're a Gamecock

[crs2k]

Wow Mr. Fosi, that has got to be the best response I have ever received on any forum, fish or not. Thank you so much!

 

To answer a couple of your questions, I do test my pH after the lights have been on for a while, usually at night an hour or two before the lights are ready to go off. So I guess that means that my pH could even be a little low during the day with the lights off?

 

In regards to the Elos test, I'll try it again and see what happens. You may be right, I was putting the drops in fairly quick, so I'll slow down and see what that yields.

 

How much does a small dose of baking soda (not washing soda) lower pH? Should I be using the washing soda no matter what because of my pH?

 

I think either way I'll bake some baking soda so I have it on hand.

 

Thanks again and I'll keep you updated.

 

Chris

[crs2k]

So I have a quick question. After reading through the DIY article, I think the best thing for me would be to do the washing soda. So once I make it and I have a gallon of water mixed, do I want to dose enough to go all the way from 6dkh to 9dkh in one shot? Would that really stress things? I am assuming I would want to do it slowly over a couple of days. Can anyone confirm that? Fosi?

 

Thanks

[lakshwadeep]

You don't want to change alkalinity (or any water parameter) so fast. It's best to do gradual additions. Check this for help:

http://archive.reefcentral.com/forums/show...threadid=102605

[crs2k]

Thanks for the link. That is A LOT of reading, holy smokes! I did read some and now my brain is just about fried for the night. I think my plan is to do a water change tomorrow, I'll test my water again, and then add some washing soda and see what happens.

 

Fosi,

I tested my water again for Mg, and I did it slower this time, and I actually got a reading of 1350, so pretty close to the previous one, and seemingly in a pretty good spot.

 

I also tested my dkh again and got a reading of 6. This reading has been consistant for me and for the LFS's that have tested my water.

 

My pH is right around 8.2 I think (it's a pain trying to match the colors).

 

My calcium was at 460, so I think I'm okay there too.

 

I'm still not quite sure about the calculator that you linked. I'm guessing I have about 12G net in my 14G biocube (being that my liverock, sand, etc. takes up space). So with 12G net and going from 6dkh to 9dkh, how much of the washing soda solution (1gallon water solution as per the recipe) should I add at one time? What would you recommend?

 

Thanks everyone, I really appreciate it!

[Mr. Fosi]

In aquariums, pH increases when your lights turn on as photosynthesis pulls CO2 out of the water. Conversely, pH decreases after the lights go out as photosynthesis shuts down but respiration continues to release CO2 into the water. So then, yes, your pH will likely read lower if you test it before your lights come on.

 

How much does a small dose of baking soda (not washing soda) lower pH? Should I be using the washing soda no matter what because of my pH?

 

It depends on the volume of your system and the volume of baking soda solution you add. In my 20H labtank (probably 17g of water after subtracting the rock volume), I added 80 mL of Randy's Recipe #2 alk and it dropped the pH by ~0.25 within 10 min.

 

I tested my water again for Mg, and I did it slower this time, and I actually got a reading of 1350, so pretty close to the previous one, and seemingly in a pretty good spot.

 

That's pretty much the ideal Mg concentration that many people shoot for.

 

I also tested my dkh again and got a reading of 6. This reading has been consistant for me and for the LFS's that have tested my water.

 

Then it really needs to come up to at least 8. You can get away with 6 if all you have is soft corals but as soon as you think you want LPS or SPS, 8 is your minimum. A good range to shoot for is 8-10 dKH.

 

My pH is right around 8.2 I think (it's a pain trying to match the colors).

 

My calcium was at 460, so I think I'm okay there too.

 

Both fine.

 

So with 12G net and going from 6dkh to 9dkh, how much of the washing soda solution (1gallon water solution as per the recipe) should I add at one time? What would you recommend?

 

That's a try-as-you-go sort of thing. It looks like you'll have to add ~51 mL of the solution to go from 6 to 9 dKH. As you read above, I just added 80 mL to my lab system to bring it from 5 to 9 dKH so you can see that I am a bit of a risk-taker.

 

Many people will tell you that you need to add it slowly so as not to shock the organisms but it has been my experience that it is very difficult to shock them when using the baking soda mix (assuming you don't raise the alk to 11 or above). Plus, when using baking soda you don't have to worry about causing CaCO3 precipitation when you add it because it doesn't cause a local pH spike like the washing soda solution does.

 

If I were you, I would add it all at once a few hours after the lights have been on (and thus when you pH is at/near it's peak). Conversely, if you use washing soda, I would add it slowly before your lights come on and not more than 10-15 mL in any given 3 hr span. You will get a greater pH spike per volume of washing soda than you will get pH depression per volume of baking soda.

[crs2k]

Fosi, thanks again for such informative feedback.

 

I'll give the baking soda a try and see what happens. I took my pH level this morning (lights had been off for about 7 hours) and I did get a lower reading. Again, matching the color on the card is a pain, but I think I was right around 7.8-8.0. So it that is the case, would it be better to add washing soda in the morning while the lights are off so I won't get a huge pH spike?

 

Thanks

[Mr. Fosi]

It'll spike no matter when you add it but you risk less precipitation if you add it when the pH of the system is lowest.

[The Propagator]

It will only spike if he uses baked baking soda. regular baking soda will drop PH slightly but rise again after 8-12 hours or so.

 

I would say with that small of a tank the hammer, candy cane, green slimmer, and torch corals are going to use up you alkalinity fairly fast. ( some tanks do any way regardless ). I generally have to add alk about every 2-3 days max. Any longer and mine will see 6's as well and that's with the magnesium balanced at 1350, and calcium at around 420.

SO you may just have to does a little each day or every other day to keep up with alk consumption.

[Mr. Fosi]

It will only spike if he uses baked baking soda. regular baking soda will drop PH slightly but rise again after 8-12 hours or so.

 

Read my posts noob!

 

I add Alk/Ca/Mg every day to keep my numbers within a tight range. If I go more than a day, my alk drops by more than 2 dKH and it is tough for me to get it back up without totally jacking the pH.

[The Propagator]

Dude you know I don't read previous posts other then the OP's original and the last post

[crs2k]

All right you two, settle down...

 

So I made my washing soda the other night, mixed with a gallon of water, and have started dosing. I still wasn't comfortable with dosing all at once (sorry Fosi), so I started dosing 1/3 the total dose (8.5mL) in the morning well before the lights come on. The first dose didn't do much. So day two, I dosed 2/3 (17mL). I tested my water that night, and I got a solid 7dkh. I thought it would come up more, but it was definitely a 7. So I have been dosing the 8.5mL each morning since and it hasn't really changed. So I guess at this point the tank is stable with this dose and I should maybe up the dose to get a little higher. Ideally, I'd like to get up to a dkh of 9. Slowly but surely. At least I'm not at 5.5 anymore.

 

Any other recommendations?

 

Thanks!

[Mr. Fosi]

So I guess at this point the tank is stable with this dose and I should maybe up the dose to get a little higher.

 

Sounds like it.

 

At least I'm not at 5.5 anymore.

 

Indeed.

 

Any other recommendations?

 

Increase your dose and keep going until you get where you want to go then cut back again.

[Lone-Wolf]

If you read Randy's DIY 2-part article, you'll see that there are two simple ways to add alk:

 

1) baking soda, a.k.a. sodium bicarbonate (NaHCO₃)

2) washing soda, a.k.a. sodium carbonate (Na₂CO₃)

 

NaHCO₃ will lower your pH slightly just after you add it and Na₂CO₃ will raise it.

 

Mr. Fosi could you use pharmaceutical sodium bicarb although I don't believe it is very concentrated... I believe it is 1 meq/ml

[Mr. Fosi]

You mean like TUMS?

[Lone-Wolf]

You mean like TUMS?

I mean Injectable Sodium Bicarb commonly used to treat metabolic/respriratory acidosis... in glass amp injected in IV

[lakshwadeep]

I mean Injectable Sodium Bicarb commonly used to treat metabolic/respriratory acidosis... in glass amp injected in IV

 

Is it sealed or opened to the air?

[lakshwadeep]

1 mEq/mL of sodium bicarbonate= 84.0066 mg/mL = 84,006.6 mg/L (ppm)

 

edited for wrong decimal point

[Lone-Wolf]

Is it sealed or opened to the air?

These are sealed amps... sterile for IV use

 

Sodium Bicarbonate Injection, USP 8.4% 84mg/mL - 50mL Luer-Jet Syringe

[lakshwadeep]

So, 84000 ppm sounds fairly concentrated.

[Mr. Fosi]

I can't think of a reason you can't use it but it seems like a pricey way to dose your tank.

 

I think lak's conversion is correct there and that's fairly concentrated when compared to the additives we usually add to our tanks at (~1070x; ~0.0785 mg/mL).

 

Are these syringes intended to be used in conjunction with a bag (or bags) of saline? Seems like a really high concentration to inject intravenously.

[Lone-Wolf]

I can't think of a reason you can't use it but it seems like a pricey way to dose your tank.

 

I think lak's conversion is correct there and that's fairly concentrated when compared to the additives we usually add to our tanks at (~1070x; ~0.0785 mg/mL).

 

Are these syringes intended to be used in conjunction with a bag (or bags) of saline? Seems like a really high concentration to inject intravenously.

This is primarily used to treat respiratory or metabolic acidosis it is generally administered at 1meq per kg so a person waying 220lbs would receive 100meq via peripheral IV access this is the common dose used in cases of cardiac arrest when patients have been down for more than 20 minutes...