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View Full Version : Precipitation from Randy's two part recipe #1


Lugnut
08/03/2007, 12:18 PM
I have a 180 gallon mostly SPS reef system.

My water parameters are:

Alk: 2.63 meq/L, 7.4 dKH
Calc: 405 ppm
Mg: 1470 ppp
Temperature: 80
pH: 8.0 before lights go on, 8.2 before lights go off

I use kalkwasser as my topoff, replacing around 2 gallons per day. It is dosed by a peristaltic pump, dripped into the sump.

So, on to my question. I have been using commercial two part additives to supplement Alk and Ca since kalkwasser wasn't sufficient. I have had no problems with those (other than that they are expensive). So, I decided to start making my own two part additive, using materials from twopartsolution.com. I mixed up recipe #1, which uses sodium carbonate, since it was the recipe recommended for the pH of my system.

When I add the alkalinity part of the commercial product, the water around where I add it gets cloudy, but nothing precipitates and the cloudiness disappears quickly. When I add my homemade alkalinity solution, the cloud forms, followed by flakes so that it looks like the inside of a snow globe.

I mixed up a batch of recipe 2's alk solution (using baking soda instead), and added some of it. No cloud and no precipitation.

So what's up? Should I use recipe #2 instead even though it says it will depress the pH of my system? Why am I getting a snowstorm? Help please :)

Thanks in advance.

bertoni
08/03/2007, 12:51 PM
The flakes might be magnesium hydroxide, which should redissolve on its own. If that's the case, the issue might be that the commercial solution has a lower pH than the DIY version. Recipe two will have a small effect on pH, lowering it temporarily.

I guess I'd try the recipe 2 and see how the pH measures up.

If the flakes are redissolving, they might not be harming anything, and you could continue dosing.

Bri Guy
08/03/2007, 10:09 PM
Take out 1g of water and practice on it, add the right amount of sup for 1g and observe, then test its results. See what happens...

MCsaxmaster
08/04/2007, 12:40 AM
A solution of sodium carbonate will have a high pH. If the pH of sea water is raised rather high (as is a local effect when this stuff is added) then magnesium hydroxide and possibly some other things will precipitate out. A solution of sodium bicarbonate has a much lower pH (~7.8). Adding this will LOWER the local pH causing no precipitaton of anything. I'd use the higher pH supplement (carbonate) but make sure that this is added to an area of very strong waterflow (right in front of a pump outlet) to promote rapid mixing. This will prevent the local pH from rising much and precipitating anything to any large degree. Also, adding it slowly will help.

cj

Lugnut
08/04/2007, 10:41 AM
Cool, I appreciate the info. I was about to change over from just pouring the two part additive into the tank to using a peristaltic pump and dosing it slowly. So I will try sticking with recipe 1 and hopefully the slow drips into the sump (high water flow area) will not cause precip to form.

Thanks again!

tcollins
08/04/2007, 12:36 PM
I just signed on due to the same problem. Using Recipe #1, I added the amount of mag (Part 3)from the calculator, waited about 30 minutes and then added the calc (Part 2), waited about 30 minutes and then added the Alk (Part 1) and instant percipitation. From reading above, I was adding to the sump and I guess I should have been adding the Part 1 into a high flow area, which is not the sump.

I was able to redisolve the participate and am guessing that everything is alright? I was going to give it an hour and test my parameters, anything I should be concerned about?

All I have in my tank right now are Turbo's and Cerinths, so no fish or corals to stress.

bertoni
08/04/2007, 02:36 PM
If the precipitate dissolved in saltwater, it likely was magnesium hydroxide, and no harm was done. The high-pH alkalinity part is best dosed into a larger volume with plenty of flow.

mattboy
08/04/2007, 06:16 PM
I notice the same magnesium hydroxide precipitation when adding the high ph alk part by hand. However, I set up a peristaltic pump (innovative aquatics w/2 channel tubing) to dose the 2 part and it works great. I'm dosing about 100 ml of each/day. That's about a drop every 5 seconds or so.

I've always used recipe 2, which is the lower ph, 1/2 strength recipe. I found I had a tough time getting the baking soda to dissolve, so I started baking it, although using the amounts from recipe 2. I also noticed that my alk was continually dropping but calcium remained high. The pump is dosing evenly; so what I did is make the alk part about 20% stronger and it's been working really well. I have no idea why Calcium and Alk were not staying balanced with the original recipe #2, but this seems to have fixed it. Since I'm just using a measuring cup to mix up 5 gallons of each at a time, it's certainly possible my amounts are off.

Lugnut
08/05/2007, 10:07 AM
I took a sample of my tank water, and dripped a few drops of the alk portion (recipe 1) into it. I got immediate precipitation, but by stirring for 10 seconds or so the precip redissolved. So I guess I am OK.

c.rob
08/05/2007, 12:43 PM
You can also dilute the solution with DI water before you add it to the tank.

MCsaxmaster
08/05/2007, 06:43 PM
Without good mixing, you WILL get precipitation of Mg(OH)2 at the very least. There is no question about that. This needs to be added to an area of strong waterflow. If it is not, expect to see this everytime...