Hi all, just thought I would post my experiences with D&D salt. I had tried 4 times over the last couple of years using this and every time it didn't mix clear. Mixing in cold r/o for up to 48 hrs. Was mixing using a large powerhead and every time it looked brown or milky. Also powerhead and bucket had brown deposits on them.
Now, after 4 times most people would give up, but as a couple of fellow reef keepers had no issues, and its I know its a good quality salt, I recently tried again. This time no powerhead, just a couple of airstones. Crystal clear in 10 minutes! Maybe someone on here could explain why? I know from other forums I'm not the only one to have this problem. It does seems a bit strange. Precipitation caused by too much flow?
The brown or white haze your seeing in the mixed water is actually calcium carbonate precipitate. As D-D H2Ocean salt contains levels of Calcium and Alkalinity found in Natural sea water it has to be mixed with some care to prevent precipitation compared with a salt that is lower in these elements.
Why do you not see precipitate when using an air pump and you do when using a pump or powerhead?
This is often due to using a large pump(compared to the mixing vessel) or a pump that runs hot internally to mix the salt. When any salt that hasnt quite dissolved enters a hot impeller chamber it will start to precipitate calcium. This is due to the warm surfaces and the fact that the concentration of salt maybe high within the chamber due to the undissolved grains being dissolved rapidly within the pump.
The precipitation can also coat the sides of the bucket leaving a brown residue similar to the tan calcium carbonate precipitate on a kettle element. Users then put this down to 'dirty' salt without actually realising that its not dirt at all and a change in mixing method will do away with the precipitate.
What can you do to prevent this?
Well you can use an air pump as you are doing at the moment as this wont add any heat. Or try using a cool running powerhead (maxijets are usually good for mix vessels up to 30-40 gallons). We also have another mix technique we have been experimenting with and found the results to be excellent.
As H2Ocean uses a naturally sourced base salt it can be mixed and used rapidly without the caustic effects of some salts made up from scratch. With this in mind you can mix and use H2Ocean salt within 4 hours of mixing, this means that pumps dont run for long enough to get hot and CO2 isnt pulled into the mix over long periods. Too much CO2 pulled into the mix will bias carbonate alkalinity to the bicarbonate phase temporarily and this can also induce calcium precipitation.
Remember that only a few Calcium carbonate seed crystals need to be formed within a warm or hot pump to kick start a cascade effect and cause further calcium carbonate crystals to form so try and keep as much heat out of the bucket until the salt has mixed well.
Hope this helps Tony
so this is what i have been doing wrong, water always clear but never crystal clear, will try these simple changes this week
Many thanks for the quick and detailed reply.
All makes sense now!
I have just rebuilt my reef and upgraded my sump to a refugium, its been cycling for 5 days and still has a brown tinge. I put this down to the miracle mud, but I don't think it is. I did a test using almost out of date salifert kits. (need to get new ones) I have readings of 280 for calcium and 6.4 dKH. The salt was mixed well in fact I decanted it into another bucket which I can open easier.(I have a disability). Any ideas on what to do next to get things back to normal?
As both of your Calcium and Alk results are way low i suggest to double check your salinity result as a low salinity will give a low concentration of all elements including CA,Alk and Magnesium. You should be aiming for a salinity of 35.5PPT, how do you test your salinity?