Plumbing// Lots of pictures to describe my plumbing

[molotov]

So I've plumbed my tank without cementing any of the fittings together. I was hoping to get some opinions or feedback to make sure I've done everything right before I cement everything. Below are some pictures with some of my comments.


I'm wondering how I can lower the tops of these caps so they're not sticking up way above the tank?




The picture below shows how far they're sticking up.



The picture below shows where the waterline should be approx. I'm wondering how deep I can submerge the siphon pipe?









The picture below shows my reservoir. The larger half will hold RO/DI water and the chamber to the right will hold saltwater mix




I've plumbed it in such a way so after I've pumped out 10% water volume for water changes I simply need to open the valve to allow the water from the reservoir above to drain back into the sump.






The plumbing with the grey 90 degree elbow will be used for ATO however how do I get my pvc plumbing to merge with a 1/4" waterline?



Again, this is the plumbing coming from my RO reservoir for ATO. The bottom plumbing will be for emergency overflow in case the sump overflows. It will run to a floor drain.



Comments/suggestions appreciated.