Could changing salt cause bloom?

Actually, you can test RO/DI for PO4 with a PO4 test kit. Because it has weakly-charged ions, it is the TDS meter that doesn't measure PO4 correctly. Some impurities have neutral ions and are not detected at all. Here's an excellent article on TDS:

What is TDS? by Randy Holmes-Farley - Reefkeeping.com

 

OK so I finally remembered to test my red sea coral pro salt.

RO/DI
Ph: ~
KH: 0
NO3: 0
phos: 0

Fresh mixed after 12 hours

ph: 8.0
kh: 13.4
no3: 0
Phos: 0

The only discrepancy I found is that i measured out the 5 gallon bucket with water and I weighed the 1.6 lbs of salt which should have given me 1.025 salinity but only gave me 1.021. I am using an old hydrometer which will be replaced soon with a refractometer.

So the batch that I have atleast does not have phosphates or nitrates in it.

 

Good to know and thanks for the update. I'm starting to think I might have phosphates from my Rodi water

 

Have you tested both rodi and new saltwater for nitrates and phosphates?

 

That's great news. On a different note, your alk is a bit high and your sg was low for the measured amount... did you mix the bucket before using? Some components settle during shipping which will cause that as well as inconsistencies between batches. I roll mine on the floor for a few minutes before opening.

 

Are you heating the water??

 

I tested for phosphates. See above

I was not heating either Rodi or fresh salt batch at the time of testing. Would heat throw off the results??

Side-bar question on Rodi, should it aerated or "moving" after being made if it will sit for a few days/week before being used for top off or salt mix??

 

Yes temperature effects salinity.Always heat the water to tank temp.
You can store RO water as long as its covered tightly in a clean food safe container.
Aerate it before adding salt mix.

 

Test rodi and nsw for ammonia.