FluvalSea Mini Protein Skimmer, 5-20 Gallon, Black, 14324 (6-Piece Set)

I gave this 5 stars, because as nano skimmers go (and I've tried 4) this one is the absolute best, even if it took a while to adjust, and even though I made a few mistakes at first. So I'm grading on a curve :)FIRST: Don't make the same mistake I did! I have a Fluval Evo 13.5, so I read the instructions too quickly and thought I didn't have to install the brackets that hold the skimmer front and back housings together (the front and back of the skimmer split open so you can clean it easily) because it was already sized perfectly for my back chamber. But, NOT installing these pieces made the skimmer really loud because the skimmer pump caused those pieces to vibrate against each other. Once I realized the issue, it was too late; I had already thrown the other extra pieces away. So I ordered another one, just to get those two pieces--they're that important! Once installed, the skimmer quieted way, way down, and in about 2 weeks, it got even quieter when it broke in (it's at about 15db, 4 feet away, measured with an app on my phone). One thing to tweak, though, is to make sure the skimmer is seated as far back against the tank's back glass as possible (away from the tank's display/overflow), so the front inlet has enough space to draw in water from the tank's overflow. I used a piece of air tubing and slid it in between the skimmer and the front of that back chamber, just to push the skimmer away from the tank overflow. That was the trick to get it to start skimming properly. Once I further tweaked water level in the chamber (the largest knob on the top) and opened the air to about 80% open (the smallest knob on the top), it skimmed super efficiently, was quiet, and I've been super happy with it. [Hack: to set the air at the right level, close the small knob all the way counter clockwise, then open it clockwise about 2-3 twists of your fingers.] You'll want the water level/surface turbulation happening right at the bottom of the collection cup. If the tribulation is happening IN the collection cup chamber, it's too high and you'll skim too wet, and it will probably overflow in no time; back it down so the water line/turbulation is exactly level with the bottom of that cup. It won't produce skimmate immediately. Give it a few hours to start producing those large bubbles and skimmate). The hardest part was getting it dialed it. But once that's done, you don't need to touch it again. When you do water changes or pour something in your tank, it will stop skimming for a bit--don't touch the dials! It will start producing skimmate again in couple of hours. Once you've got it dialed in, you'll be impressed. I sure am.

Update 3/21So a couple of things to note. Putting the air valve in the cup lid was ridiculously hard. Not a problem I encountered during the first skimmer I ordered and returned but it was a ....welcomed problem.... with the first skimmer, the valve would come off the lid easily and needed to be in the exact position to not move the lid nor disconnect itself from the lid. With the second skimmer, after shoving the valve into the lid with sheer strength, it doesn't move now which keeps the lid in place and valve from coming off. Also, the knob on top of the valve I had to take off because it was sealed. I have it completely removed as it serves no purpose, since , it's clogged. I tried putting a needle through it but it feels like there's a pieces of plastic inside. Now, after some diy with silicone, the skimmer is working beautifully! Has been taking out gunk and keeping my water nice and clean. A lot of alterations to get to this point but it is finally doing its job.I ordered the skimmer for my fluval flex and though it's ideal for the tank and the evo, it does have a huge design flaw. The casing on top does not seal correctly no matter what and leaves a small opening between the cup and housing. Water ends up going back into the sump area which defeats the purpose of a skimmer. I used some silicone to seal the tiny gap as my skimmer options are limited. Water level is finicky but the gap is a huge problem. Returned the unit and ordered a second one and same gap is found. Diy steps will be needed

I don't know why so many people say this skimmer is poor or hard to adjust, I think this skimmer is fantastic!. I have had it in my Fluval Evo 13.5 for 6 months now without a hint of a problem. Originally it was in chamber 1 as intended, I later "upgraded" to the InTank media basket (waste of money) and moved it to chamber 2.It is the only nano-skimmer I have found that has 2 adjustments: water height and air flow (bubbles).It is simple to adjust, watch a youtube video if you want but all you do is turn the larger knob until the water line is where the bottom edge of the cup meets the skimmer body then adjust the airflow (smaller knob on top) until the bubbles are just below in the inside lip of the cup. That's it. Very simple!Note that ANY skimmer you buy will take about 3 days until you have it "broken in" (slime layer developed, adjusted perfectly for your situation) after that it's kinda auto-pilot. Each water change, I tweak a knob a little but that's it.In my Biocube 32 I have searched out an equal performing skimmer and have bought 3 so far, none have worked as well as the Fluval in my Evo 13.5. The Tunze 9001 goes in chamber 2 if you get the InTank media basket (well worth it on the BioCube) as does the AquaLife 115. Chamber 2's water level flucuates so much that either are almost never skimming. Unless you spend $200 for a good automatic top-off system they are useless IMHO.The Coralife skimmer designed for the Biocube 32 fits in chamber 1 so the water level remains constant but the skimmate is never dark, probably because it does not surface skim. It also adds special limewood airstones to changemonthly.Believe me, this Fluval is GREAT and I may breakdown and cut a whole in my Biocube lid to fit one just so my wife stops laughing at me and saying "you bought another skimmer? LOL"PS- anyone want to buy some slightly used nano-skimmers? LOL JK

I loved it. It cleared my tank and made the water look clearer but it’s just too loud for me. I’m not sure if they are all like that but mine was