Sustainability concerns in ecosphere

[aaronremark]

Hey guys! I'm new to the hobby and aquatics in general, so please forgive my lack of knowledge, overall ignorance and potential idiocy.

I recently got a small (~1/2 gallon) open ecosphere as a gift from my parents for college, and it has around 15 shrimp. I wanted to make it more diverse/lively by adding some small tankmates, and after some research, decided to add a horned nerite snail and MTS. Of course, no one is selling either individually, so long story short I now have 2 MTS, 4 HNS and 15 opae ula in my half gallon sphere. Following this, I worried I might've thrown the nitrogen cycle out of whack and bought an algae ball and macroalgae from here. Overall, it looks really nice. The snails are adorable roaming the glass, and the shrimp have fun playing with the ball, but I have a few concerns about this setup.

After a few days with the snails, I noticed a clear reduction in the visible algae on the substrate. In the image I'll attach, the bottom still looks pretty green, but trust me it is a definite decrease.) So, I've been wondering if this is going to be a problem or if it's just a matter of aesthetics. Will the combined demand of these animals exceed the algae/biofilm's ability to grow? Was it a mistake to add any snails, let alone six of them? On a separate note, is the macroalgae I added going to outcompete the algae they need to eat within the confines of this small system?

Here's a pic from 6 days ago. The shrimps are munching on a calcium/protein tablet (pretty cute right?). I would attach a more recent picture but the water is a bit murky at the moment (I, perhaps haphazardly, added some live spirulina hoping it would help) and wouldn't be of much use.

I really don't know what I'm doing, so if anyone more experienced than me with this type of thing could weigh in, any questions/advice/reassurance would be greatly appreciated.

[Vorteil]

It is fine the way it is. No feeding. All you'll have to do is top off the water with RO freshwater. You don't have to do anything else. Don't add any live spirulina. You can feed freeze dried spirulina but very little and that should be at the beginning of it. A horned nerite will not work in a sphere this small. There won't be enough algae in there to sustain it. It will starve in there.

[aaronremark]

Thank you for the reply. Unfortunately, I've already added all of these things to the sphere. I'm willing to rehome the nerites, but I should have clarified they are the zebra thorn variety which only grow to maximum 1/2 inch, much smaller than other nerites. What if I just kept one in there? Otherwise, are the trumpet snails fine in there? What about the macroalgae?

[Vorteil]

Trumpet snails don't require & that's why they're best suited for Opae Ula environments. There's just not enough in there to sustain a nerite snail. Their requirements are much more plus you have to consider making sure there's enough to sustain the shrimp. This doesn't mean feed more unless you're planning to do water changes. Keep in mind what you have is a shrimp that requires very little so you don't want to throw off the balance. IMO there's too much in there to safely support a Nerite snail. You can try but if it doesn't work in the long run this may be why.

[aaronremark]

Okay, thanks for the advice. I went ahead and took out 3 of the 4 nerites (and 1 MTS) but left the smallest one (which is about 3/16 inch in diameter) for now. I figure since it's so small it shouldn't be an issue, but I'll monitor it closely to see if the substrate regains its green color or for any signs of distress. Thanks again!