I started with a sterile tank, but with Reel Reef rock and Carib Sea live sand. They are supposed to be free of pests. I didn't want to start out with the pests you get from actual ocean live rock.As you can see there are a LOT of opinions on how to start seahorse keeping. Indeed there are MANY ways to succeed.
My 18 years of keeping has impinged on me the degree of attention needed to water quality probably over and above any other need, especially as test kits we have DO NOT tell us when bacteria (the biggest killer) are going to be problematic.
However, for STARTING a first tank, the immediate concern is to make sure the cycle has completed so that our seahorses don't get exposed to any levels of ammonia when inhabiting their new home.
So it really doesn't matter a lot HOW you cycle the tank, just that is IS cycled. The way to determine if the tank is cycled properly is to CHALLENGE the tank once you think it is ready. To CHALLENGE the tank, add an ammonia source like pure ammonia liquid or ammonium chloride powder so that the ammonia level goes up to 2ppm or higher depending on just how much load you will be placing on the biological filter right off the bat. If the ammonia clears overnight, you should be good to go. I've never waited 6 months or even six days before adding the seahorses after the cycle has been challenged successfully, although I DO usually challenge the tank two days in a row just to be sure.
Use of the variety of product aids for cycling is just a personal choice and not a necessary one.
I have personally never used anything other than ammonia or ammonium chloride to cycle a tank but again, that is just my choice.
I much prefer also to start a tank off COMPLETELY STERILE, with only artificial hitching and no other tankmates. This way if something does go wrong, I have already eliminated a lot of possible sources of any problem that develops. This was extremely important to me until I gained some years of experience. (it's also a GREAT way to be sure you won't have to deal with aiptasia or bristle worms)
Back to water quality, as there are no test kits available to the hobbyist to tell us when the bacteria are going to be a problem, it is obvious to me that husbandry and water change protocols need to be what many consider to be excessive so that you don't have to end up treating severe problem cases that develop. Figure out what you THINK you need to do and then do even more.
You can accomplish the water quality by doing frequent and large water changes as I do, or as many others do, lesser water changes but using more equipment to clean up the water dirtied by the way seahorses take in and digest their food. A greatly oversized skimmer goes a long way to help this.
That all being said, if you are MORE comfortable waiting longer, even 6 months, then go for it. It isn't going to make anything worse, and MOST of the pods you may introduce if the system isn't sterile, will be smaller than the seahorses are going to be interested in. Amphipod size though would be ideal.
Again on my personal outlook, I've never added pods or anything not sterile until well over a year into a tanks setup.
How do I challenge the tank? I am using ammonium chloride in my cycle, but I don't know how much to add to raise it to 2ppm to clear it overnight once I've finished my Dr. Tim's cycle. I have a 54 gallon tank and 26 gallon sump that have a total of 70 gallons of water (after rock and sand displacement). Do you have a forumula/recipe? I have a huge skimmer (way oversized for my tank) and a very large chiller to make sure the temp stays low (70-74 degrees). I tried my best to overbuild my tank to give myself the best start I could.
I was planning to add copepods and amphipods to my sump. Should I wait or is this a personal thing? I'm also going to add macro algae in the sump. I plan on sticking to artificial hitching posts for a while, too, and only adding a few other seahorse safe fish.