[lightcycler]

I've screwed up here. I have been mixing a batch of saltwater for about a week. I didn't have a heater in it. Got the salinaty close and was going to adjust after I got the water heated up. (Have a heater on backorder so stealing the one from my tank) I added baking soda to adjust the pH and now the pH has dropped and the calcium has precipitated out. I'm using a powerhead to mix.

Right now I'm raising the temp in hopes to get the precip back into solution.

Need a little advice. I'm thinking I should wait to add the baking soda until just prior to doing the water change?

[leebca]

Newly prepared saltwater from a salt mix, made to relatively 'normal' specific gravity usually doesn't require much in the way of a pH adjustment.

Sodium bicarbonate, if needed, is used very little in this adjustment.

If there is now a precipitate after adding the sodium bicarbonate, then I am afraid that there has been some precipitation of carbonates from the salt. These carbonates will not go back into solution (even with heat). I would discard the batch. But I would also be very sure of what you're doing.

How did you check the pH of the saltwater in the aquarium? in the new water? after the addition of sodium bicarbonate? This should not be done with a test kit and the use of color indication. Test kits are not accurate nor precise enough. The proper procedure is with a pH meter that has been properly standardized/calibrated.

[lightcycler]

Originally Posted by leebca

Newly prepared saltwater from a salt mix, made to relatively 'normal' specific gravity usually doesn't require much in the way of a pH adjustment.

Sodium bicarbonate, if needed, is used very little in this adjustment.

If there is now a precipitate after adding the sodium bicarbonate, then I am afraid that there has been some precipitation of carbonates from the salt. These carbonates will not go back into solution (even with heat). I would discard the batch. But I would also be very sure of what you're doing.

How did you check the pH of the saltwater in the aquarium? in the new water? after the addition of sodium bicarbonate? This should not be done with a test kit and the use of color indication. Test kits are not accurate nor precise enough. The proper procedure is with a pH meter that has been properly standardized/calibrated.

I check my pH with a field meter. Calibrated it yesterday. My main tank is at 8.2. This makedown water is now at 7.6. This precipitation has happended to me twice now. First in the QT. Part may have been using a small HOB filter. Wal Mart didn't have any sponge filters but I"m ordering one now. I used Kent Marine Salt the first time. Mixed the baking soda in DI water to add to the system. Got the white precip all over my 10 gallong QT tank. The 20 gallons I was making for the water change was with Coral Life Salt with Calcium and Magnesium. Not growing coral but thought it would help the coraline algae.

In the makedown salt water initially I didn't have a powerhead until it arrived in the mail and then I added it. Positioned it on the bottom moving the water up. The precip happened after about 6 days of mixing. Again the water was at room temp. 70 probably.

I am going to dump this batch and start over and see what my pH is exactly after 24 hours.

Does anybody use like a 1N NaOH solution to adjust ever? My 75 gallon tank is doing fine and buffering nicely.

I will wait till shortly before I'm going to do the water change to make small adjustment to pH. If I remember I was trying to move from 8.0 to 8.2

[leebca]

I'm unfamiliar with the term 'makedown water.' Is this the source water?

Sodium hydroxide is useable, too. But changing the pH slightly should not create a precipitate if the salt mix is proper.

[lightcycler]

Originally Posted by leebca

I'm unfamiliar with the term 'makedown water.' Is this the source water?

Sodium hydroxide is useable, too. But changing the pH slightly should not create a precipitate if the salt mix is proper.

Yes by madedown water I mean water to be used for a weekly water change. The precip sure appeared to be calicium carbonate. Got a good fizz when I added acetic acid to clean out my 55 gallon rubber maid. I think I got too much CO2 some how into the mix? Well I'll keep working at it.

[lightcycler]

Thought I would update on my new batch of saltwater for tank water changes.

My DI water has a pH of 8.4. Now have a sp gr. of 1.022. adding more salt to get to 1.0235 which is where the main tank is for sp. gr. right now Mix is clear with a powerhead moving the mix. pH now is 8.0 for the batch I am making. I'm sure it wouldn't be a big deal to do a 10% change with this water at 8.0? The tank is well buffered now. I'm a bit skidish about adding baking soda at this point. Have had no problems in the main tank.

[leebca]

Taking the pH of pure water can be misleading. The pH meter needs ions in the water in order to accurately measure pH.

You mentioned the pH of the new water, but I don't see where you mentioned the pH of the tank water you want to make the water change on. So, I don't have the information on which to help you with your question.

Generally, a 10% change doesn't have a large impact on the water quality. If the new water is added slowly there can be small difference in pH and still not negatively impact the fish.

I don't know the volume of the water you made up, but adding sodium bicarbonate to it to raise the pH would take a small amount.

[lightcycler]

pH of the tank I'm adding the water to is 8.2. I think the problem was one of overdosing the sodium bicarb. In 10 gallons maybe 1/2 teaspoon? I always disolve in pure DI first. Going from 8.0 to 8.2

[leebca]

I would add the sodium bicarb to the mixing salt solution. I would add very little at a time, let it mix for 5 minutes and read the pH before adding any more (if needed). Just go slowly. Try out a pinch and see what effect it has rather than trying to set an amount (like 1/2 teaspoon) to add. Go slow and add little amounts, multiple times if necessary.

[lightcycler]

Wierd stuff. I added some baking soda. Just a pinch. The pH seems to drop. I'll let it mix and measure again when I get back from my trip on Friday. After a short mixing time the pH dropped to 7.5

[lightcycler]

Lee I have my powerhead on the bottom pushing the water to the top. There is a decent ripple on the top of the water. The mix is only 24 hours old at this point. pH is steady now at 7.5. Kind of afraid old Arm and Hamour doesn't like my DI water? I'm at a loss at the moment. Has to be forming carbonic acid? Heck I don't know

[leebca]

I'm assuming that your 7.5 reading is BEFORE you'ved added anything to the mix other than the salt and water? No pH adjustments, right? Then, there is definitely something wrong. The starting pH at the proper specific gravity should be within 0.15 pH units of where it belongs.

Test your source water (what you call DI) for pH, but this time, do it like this:
Take a pint of the pure water you're using (no salt). Add a pinch of table salt. Mix it well. Take the pH. It should read about 7.

If it does, then something is wrong with the salt you are using, the container/equipment, or the place you are mixing it. You should be mixing it in a room or place where there is fresh air, not contaminated or impure air. Is the container clean? The container and equipment should have not been used for chemicals, foods, or any other products, but it should be new, off the shelf. If you are right on these, then I'd contact the manufacturer of the salt by e-mail or phone and ask them to explain why the salt mixture doesn't come into the proper pH. This may not be a problem for you, it may be a problem for the salt maker.

Bad salts have been bought before. Salt providers are not infallible and quality slips now and then. Get the batch or lot number of the salt you are using before calling them.

This pH change is not at all proper, expected, nor normal. Don't make the water change until this has been resolved.

[lightcycler]

The pH after adding the salt was 8.0. Then I added some baking soda and it immediately dropped the pH. Waited and added some more. The pH dropped to 7.5 and thats when I had to catch a plane. I'm taking the pH with the powerhead moving the water. Knowing in the lab we test pH with a stir bar. Thats the bad thing here. I'm a chemical engineer and 10 years of managing lab experience. Mostly Micro these days but lots of chemistry in past.

The salt mix appeared to be fine. I would think 8.0 is not bad. Addition of the sodium bicarb dropped the pH. I'm using a 55 gallon rubber maid that was not used for anything else. Bought new at Wal Mart. The room is my utility room which has my hot water heater, washer and dryer.

Would the powerhead introduce CO2 if positioned wrong?
Maybe I need to move to another room?
I will check my DI water and get the make and model of the system. I bought it off of EBay from Filter Direct.
WaterGeneralReverse Osmosis+DI Water System Made in USAModel: RO 6102 DINT6-stage 110 gal/day Reverse Osmosis Water System+2DI filters (stand alone unit, no drinking faucet, no pressure tank)
(optional TDS water quality meter, UV system, pump system, also available, check our other items on ebay)
This system is a 6-stage 110 gallon per day reverse osmosis + 2DI filter system with single outputs (mainly for Aquarium and Reef). We use 2 Nuclear-grade color changing DI filter with refillable Clear housing and DI dispensing ball Valve for applications like Reef, Aquarium, hydroponics, humidifier, jewelry cleaning, any application requiring ultra pure water.
Tap or well water ---->after RO system --->after 2DI filterwater purity about 300 ppmabout 15 ppm

[leebca]

The laundry room may be the room you'd like to use least. Chemicals used in the cleaning of cloths usually fill the air. Even if the laundry room is well ventilated, there is too much of a risk of those chemicals altering the new water.

Is the baking soda fresh? It has a shelf life for this kind of use. If it has become moist after opening, it could be a problem. If you're using a fresh/new box you just bought, that would eliminate this concern. Also be sure the baking soda is pure, without any additives.

If you take fresh baking soda and put it into the preheated oven at 350F for 40 minutes, you can convert most of it to sodium carbonate which is a stronger alkaline chemical. If that doesn't raise the pH, then there is still something going on I don't see. 'Course, if you do have access to sodium hydroxide, just use it sparingly as a trail and error until you move the pH to where it belongs. I use NaOH pellets in my batches.

Hope you travel safely.

[lightcycler]

I'll check the baking soda but it was a new box just purchased. I'll move my mixing out of the laundry room. And I do have acess to NaOH in varied strengths. The pellets sound like a good idea. Thanks for continuing to work through this with me. So many variables. My tank is coming along nicely about two months into the startup now. Really need to start doing the water changes but all parameters are doing quite well at the moment. Just don't want it going south on me.

[DonW]

Originally Posted by lightcycler

I'll check the baking soda but it was a new box just purchased. I'll move my mixing out of the laundry room. And I do have acess to NaOH in varied strengths. The pellets sound like a good idea. Thanks for continuing to work through this with me. So many variables. My tank is coming along nicely about two months into the startup now. Really need to start doing the water changes but all parameters are doing quite well at the moment. Just don't want it going south on me.

I dont understand why you are using baking soda for this. If your having problems getting ph up on NSW, Id look at the mixing method and otherwise ignore it if its a little low. Adding baking soda is increasing your alk and and dropping the ca along with the mg. Test temp, ca, mg and alk on the fresh mix and balance it accordingly that is all that is needed prior to a water change.

Don

[lightcycler]

The reason for adding baking soda is that being new to the hobby I thought I needed to match the pH of my tank. Also had the same problem with my 10 gallon QT. Tried to adjust the pH and ended up dropping the precip out all over the place.

Quite frankly I've been searching for info and I know how to adjust pH using some NaOH. Just need to get out of the box I was in thinking I needed to use Baking Soda. I'm sure I over saturated the water and......it crapped out. I've got to believe that others have gone through the same thing in the beginning. At least I've learned some lessons at a point where its not an emergency to make the water change and I don't have fish yet. Thanks for all the help.