That 25L tank comes in black or white, so whichever you prefer. I always use ProShrimp as they are almost always the cheapest and give great advice and service. As stated before the built in box is a bit big so if you decide you want to remove that when you get it let me know, there is also a youtube video on how to do that. The only thing that occurs to me is that the top FLIPS up one side or other depending which way round you place it (with the light built in) so is there enough open room above for it to flip up in the place you plan to keep it??? I will try and get friends to take a photo later so you can see what I mean. But if you look at the below video you will see the flip top and interior box. The built in box can house the heater but only if it is the usual glass tube type and I don't like/use those so that is part of the reason I removed the box, but I wanted to remove it anyway as I didn't like the look and it s quite big.
https://www.youtube.com/watch?v=eZ6atIFs1_Y
I understand what you are saying about the filter but it can be below the water level and oxygen is still absorbed into the water - that is way over my head though and I don't know how it happens. When I used the 15L it had an adjustable nozzle so I pointed that upwards, it was always under the water though. I BELIEVE as long as there is water movement there will be air absorbed.
I think my friends are taking me to a place about 20 minute drive from here called WATERWORLD. Usually they just get something for me if I need it but they insist on getting me out, which I am looking forward too (also nervous about though, but I won't be alone) as I haven't left the house in over 2 years............... I have heard of maidenhead aquatics and I believe that is where friends usually go if they are getting something for me, or themselves.
It is easy to get drawn into the colourful shrimps. I don't know whether the Platys will eat really tiny baby shrimplets but with plenty of moss and hiding places they wouldn't get them all! I have put the culls in the new Betta tank as they are brown and almost impossible to see. When I did this before it worked as the Betta didn't seem interested in them as maybe he didn't see them, I'm not sure but he may have picked off some shrimplets, but again I don't actually know? They are culls anyway so if he enjoys them, good for him.
Sorry about the Late reply but I went to bed early in preparation for todays excursion.
Simon