It’s good to hear that your seahorses are doing well!
Most everybody enriches the frozen Mysis with Vibrance a little differently and in actual practice there are probably about as many ways to successfully accomplish that task as there are seahorse keepers. But I would suggest changing your method somewhat so that you are adding the Vibrance powder to the frozen Mysis after it has been thawed and rinsed, rather than adding the Vibrance to the water the Mysis have thawed in and soaking them in the Vibrance. It sounds like when you subsequently suck the enriched Mysis up in your baster, you are releasing a lot of excess Vibrance that has dissolved in the water into your aquarium. The excess Vibrance that goes into the tank this way won’t do the seahorses any good and could degrade your water quality or fuel the growth of nuisance algae. Here are some techniques for enriching the frozen Mysis that work well for other hobbyists:
Tips for thawing and enriching frozen Mysis.
In order to prevent wastage and obtain the maximum benefit from this superb food, it must be thawed properly. This is especially important because once the Mysis are fully thawed, they are not refreezable (Adib, 2004). Most hobbyists tend to simply thaw their mysids in aquarium water, which has the virtue of thawing it quickly but is not the best approach. The faster the frozen shrimp is thawed, the more likely it is to be damaged in the process. We want the mysids to remain intact and lifelike; we don’t want the tissue of the Mysis to begin to breakdown in the process of freezing/thawing. The goal is to preserve the Mysis and retain all those precious shrimp juices when we thaw it, not to release their fluids into the aquarium water where it will only degrade the water quality and do your seahorses no good!
So don’t thaw frozen Mysis in 75-80 F aquarium water. Don’t nuke it in the microwave to defrost it! And don’t simply toss a chunk of frozen Mysis in your tank and let it float around until it thaws and releases individual mysids!
Nor should you thaw it in tap water, distilled water, or any other source of freshwater. You want to thaw the shrimp in water that is about as salty as their own bodily fluids so there is little or no difference in osmotic pressure. Freshwater will tend to move into the mysids as they thaw and can break down their integument and rupture cell walls as they swell; excessively salty water will tend to draw water out of the Mysis as they thaw, desiccating them in the process. Normal strength seawater is just right for thawing.
So the recommended method for thawing frozen Mysis is to use refrigerated saltwater from your aquarium. Keep a small jug of your artificial saltwater in your refrigerator and reserve this for thawing your mysids (Adib, 2004). Place a couple of ounces of the chilled saltwater in a small cup or similar receptacle and use that to thaw the shrimp. Break off a small chunk from the mass of frozen Mysis — just enough for one feeding or a day’s worth at most (with experience, you will soon learn exactly how much to use) — place it in the cup of saltwater and allow the Mysis to slowly thaw in the refrigerator for 30-45 minutes (Adib, 2004). Then take the cup out of the refrigerator and allow the thawed Mysis to warm up at room temperate for another 15 minutes (Adib, 2004). This method leaves the mysids perfectly intact and lifelike, and produces immaculate shrimp that need no further rinsing. (If you use another method for thawing the Mysis, it’s generally advisable to rinse the thawed shrimp in a brine shrimp net to prevent clouding of the water.) You are now ready to fortify the Mysis with the enrichment formula of your choice.
Carefully remove the individual thawed mysids from the thawing container using a plastic fork or a toothpick and gently deposit them in the bowl of a plastic spoon. The idea is to handle the shrimp as little as possible during the thawing and enriching process, since rough handling can cause the mysids to break apart. If your enrichment product is in powder form (which I recommend), take a pinch of the formula, sprinkle it on the Mysis, and mix it in very gently (a plastic knife or similar instrument works well for this step). The orange power will adhere to the moist Mysis, and when you’re done, the head region (cephalothorax) of the mysids should be stained reddish. (If your preferred supplement is a liquid formula, just add a few drops to the Mysis and let it soak in.)
With a little practice, most hobbyists quickly work out their own technique for preparing enriched Mysis. The method outlined above works well for me and many other aquarists, but there are many other ways of defrosting and enriching the Mysis that work equally well. For instance, other hobbyists prefer to add a dusting of enrichment powder (or a few drops of a liquid supplement) to a chunk of frozen Mysis and gently mix it in (or allow it to soak in) as it thaws. One nifty way to do this is to break off my little chunk of frozen shrimp and place it on a square of wax paper, allow it a while to defrost, and then add a pinch of enrichment formula and roll the Mysis and power in the wax paper as though making a cigarette. This technique is trickier and takes a little experience before you can pull it off properly. The thawing and rolling/mixing process must be done very, very carefully or you may crush some of the Mysis and lose a lot of shrimp juice while preparing it. As always, if you’re doing it right, the heads of the individual Mysis shrimp should end up stained red, which is a feeding "trigger" captive-bred chowhounds find hard to resist. With a little practice, you will soon refine your own method for preparing frozen Mysis that works the best for your schedule and the needs of your herd.
But however you prepare it, it’s important to keep the enriched Mysis refrigerated until it’s used, and to use all the Mysis you thawed and enriched within 24 hours. For best results, the enriched Mysis should be used immediately after it’s prepared. Whether it’s been refrigerated or not, avoid using thawed and prepared Mysis that is 2 or 3 days old. We don’t want to offer our seahorses food that might have become laden with bacteria.
Best of luck perfecting the enrichment method that works best for you and your seahorses, FERS4REEF!