Different systems behave differently having recognized that, I am always testing different things to optimize my own. Regarding salts I use quite some, I make 50 gal water change per week on a system with 225 actual water volume with mostly SPS corals. I have found out that different salts have been formulated differently for different uses or to be mixed with different source of fresh water.
As an example Oceanic is supposed to be used for reef aquariums were Calcium and Magnesium are important unfortunately it seems to be formulated for a salinity of only 1.021 to 1.022 so if mixed to 1.025 to 1.027 full NSW strength chances are you will exceed the Calcium and Magnesium parameters. When Oceanic personnel were consulted in this regard they seemed rude and practically blamed me for mixing it at that high 1.025 salinity.
Another example is Crystal seas Marine Mix. This salt seems to be formulated to reach close to the parameters at 1.025 but assumes Tap water is being used so takes into account the starting hardness. Also because it assumes Tap water it includes dechlorinator in it's formulation.
Kent and Reef Crystals seem to be oriented toward reef use as it contains more trace supplements and somehow higher calcium and Magnesium than IO. If mixed to full NSW strength (1.026 to 1.027) these are the salts that mostly approach reef requirements although will fall a little short. The reason seems that the formulation is set not to risk much precipitation if mixed with tap water. Also the manufacturers (do not know why) recommend mixing to 1.023sg when in reality better parameters will be reached at full strength.
IO seems to be a general purpose salt which will be suitable for Fish Only mixed at 1.021 to 1.022. For reef at 1.025 1.026sg It achieves good alkalinity level but will need some Calcium and Magnesium supplementation.
In general solubility seem to have been a marketing blitz. Oceanic given the finely powder grind seems to be the one that dissolves faster but with enough agitation I have not really seen an advantage in one dissolving in 5 minutes and the other in 10 mainly if I consider that even when the salt is dissolved, the contained elements like Calcium Chloride, Carbonates, Bicarbonates, and Borates need at least 4 to 6 hours (with 24 Hrs) recommended for PH stabilization.
I have tried IO, Kent and Oceanic. With Oceanic I had some unexplainable algae bloom and had more difficult controlling my water parameters. Kent and IO would be my favorites. Kent has been the one I use the most and have been using long term basically I can control the end result of the mix, dissolves very well with no residue using RO/DI and is so consistent that I just add my present scoops of salt, and supplements and although I test for Salinity, Calcium, Alkalinity and Magnesium I have never had to correct the amounts. I have gone trough about 20 200 gal buckets of Kent and only once I had an issue of extremely high alkalinity like the issue IO had some time back. I contacted the distributor and within 20 minutes I got a call directly from Kent's Manager to give me the track number of a new bucket sent overnight and to provide me with a UPS account for me to send him some samples. Great service when you need it most.
Regarding my tests of the Oceanic. With all the hype about it I got three buckets to try it. I initially liked the Calcium and Magnesium Levels but not the alkalinity levels. At about the half of the second bucket I started noticing algae I had never seen before, nothing like diatoms but more like brown algae that I originally though it to be dinoflagelates but started by forming some hard spots (like coralline) that when left to grow turned hairy (pics to follow). I started suspecting the salt when I started getting brown stuff in my mixing tank so I started the serious testing. The following four batches of the mix were fully tested:
In the four batches RO/DI water tested undetectable for Ammonia, Nitrites, Nitrates, Phosphates or Silicates. (I use a 100 gpd Spectrapure system with 0.5 micron sediment, 0.5 carbon block, high rejection 98.5% TFC membrane, Silicate Buster DI resin cartridge and mixed bed electronic grade resin. Monitor set up to alarm at 0.3 ppm of TDS.
Mixed prepared in a 50 gal batches on Polyethylene graduated tank, mixed with a Magdrive 9.5, and aerated 48 hours using a linear diaphragm pump withewater LT15
The range I got from testing the Oceanic:
Ammonia Undetectable (LaMotte Salicilate test method)
Nitrite_N Undetectable (LaMotte)
Nitrate-N 1 to 3 ppm (LaMotte)
Silicates 0.5 to 1 PPM (Salifert double checked with Hach)
Phosphates 0.06 to 0.5 PPM (Hach)
Calcium 480-530 PPM (Salifert)
Alkalinity 140 to 165 PPM (LaMotte) (2.8 to 3.3 meq/lt)
Magnesium 1320 - 1480 (Salifert)
Iodine Not detectable (Salifert)
Salinity 1.025 Refractometer
Temperature 78.5 to 79.1 Lab glass thermometer
Water heated with two 350 watt Won Bros Digital Titanium heaters.
Water Mix Color: Light Brown
Precipitation: Minimal
Tank walls stained with brownish material relatively easy to wipe off with a towel once tank empty.
Tank was covered during mixing and aeration in dark room.
After those tests I decided to switch back to Kent's. For the switch the mixing tank was washed with vinegar, scrubbed clean with bleach filled with RO/DI water added bleach again and let recirculating for 48 hrs. Emptied and flushed twice with RO/DI again.
I tested the Kent's following six batches the same way and equipment used for the Oceanic Tests.
Ammonia Undetectable (LaMotte Salicilate test method)
Nitrite_N Undetectable (LaMotte)
Nitrate-N Undetectable(LaMotte)
Silicates Undetectable (Salifert double checked with Hach)
Phosphates Undetectable PPM (Hach)
Calcium 360 to 380 ppm(Salifert)
Alkalinity 175 to 180 PPM (LaMotte) (3.5 to 3.6 meq/lt)
Magnesium 1170 - 1190 (Salifert)
Iodine Not detectable (Salifert)
Salinity 1.025 Refractometer
Temperature 78.7 to 79.2 Lab glass thermometer
Water heated with two 350 watt Won Bros Digital Titanium heaters.
Water Mix Color: Clear transparent
Precipitation: small amount of small white granules
Tank was covered during mixing and aeration in dark room.
The algae started to diminish and after the fourth water change (about a month) it was completely gone.
Having trusted that the algae could have been just a cycle and or the Oceanic has been a bad batch I stubbornly (Price had something to do with it) I ordered a new batch of six more Oceanic buckets and started using it again.
To make a long story even longer the same algae returned after the second water change.
Switched back to Kent and gave away the remaining buckets of Oceanic never to see them again.
After eight months no signs of any algae.
Unfortunately with Kent I have to continue the Calcium and Magnesium buffering so no savings there.
So if Oceanic works for you, and I know some great systems that use it; stay with it as your system may react differently, if you start having chemistry stability or algae issues try something different and stay with whatever suits you best.
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