TLDR All responses but saw a few...
You can keep SPS in a month old tank if you're an experienced reefer. I only bring this up as there's a lot of time's people just throw out "Your tank's not mature enough" Which in all honesty I've only seen trouble with Nem's and ACTUAL tank maturity ever. which is because I've a hunch Nems are very Bacteria and microbiome sensitive, which a lot of new reefs have these out of wack
Microbiomes.
I've never been able to link coral dying to a "tank" being too new. Rather the tank was "new" and so was the reefer.....
Case in point.
https://www.reef2reef.com/threads/my-new-sps-tank.674002/page-23#post-10115245
Look at this guy's bare bottom. But he's an Experienced reefer. He packed his tank with SPS after 50 days and I'm pretty sure he used dry rock as well.
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With that said. You also are having problems keeping LPS alive, Euph's to boot, which in MY experience have been some of the easier to keep alive LPS.
you can keeps LPS and SPS in the same system, you can have a mixed reef. They will all be happy and survive just fine and grow if you know your stuff.
Anyway point is. Slow down a bit, if you're having trouble with LPS there is a REASON why. You need to find the REASON, that's the biggest learning curve in this hobby and where a lot of people give up is not being able to "solve" whatever it is that's actually going wrong, and then moving on to " something else" in hopes it'll work, but eventually it all spirals and snowballs into crashes and people leaving the hobby and they never post here again. If you're having trouble with your LPS you'll have STN on all your SPS and then be posting back here "Why are my SPS tips bleaching out" etc etc. Which we'll help you then, but it's better to just figure out what you're not fixing in your current system now.
With that said my TIPS for SPS is STABILITY is KING with SPS. It's not about #'s it's about Stability in your system, finding your own systems "equilibrium" and then planning and working to make sure it stays in that band with the smallest margin of error possible. (Ideally as naturally as possible too, which is why a lot of people refer to "maturity" with a tank as the more mature the easier that becomes to achieve naturally). As your tank grows, ages and changes, you will have to constantly adjust your schedules and dosing etc as well, and if you're not ready to be in a never ending chemistry/science world, (At least til the tanks a few years old and you've got your thick reefer skin by then) then don't do it.