OASE CrystalSkim 350 Surface Skimmer for Freshwater and Marine Aquariums – Compact Internal Filter for Film Oil and Debris Removal, Quiet, Adjustable Flow, Shrimp-Safe, for Tanks up to 92 Gal / 350 L

This is actually one of the best surface skimmers I've owned and to be fair to other manufactures has a lot to do with design improvements over the years. Some others I've used in small tanks are: Eheim Skim350 (excellent skimmer but not for small fish unless install custom netting over the inlet); AquaNeat (budget price, decent but not best); ADA Vuppa II (quality built, pricey, skims well, motor mechanism prone to failure). What I like about the Oase 350: excellent skimming, inlet/outlet designs, pricing, functionality.

It is not something you plug in and solved everything. You need to 1. Adjust the placement with the water level and when it is right, you will see the oily film running toward it. 2. Clean the filter regularly to continue working. 3. It can also be used to remove the duck weeds and surface trash. 4. For a 75 gallon, only one side will be able to cover, so you need to move to another side to clean the other side. It will not work for lazy people.

Great skimmer. Perfect size for 20 gallon high but needs to be at lowest power if you also have a wake maker. The little thing can create a CRAP ton of micro bubbles at full power. The only complaint I have is that the sponge filter has too large of pores for my needs of filtering out silt. While it still filtered out some silt, I have purchased a sheet of aquarium sponge to custom cut to the size. Honestly, if you spend a couple bucks on a better quality sponge, this skimmer is worth the price! It is very small but powerful and doesn't any noise if installed correctly. The skimmer is the only filtration I have in my tank and it is working great!

The best tip is to read the instructions! It will tell you how to install and adjust the flow. Choose the lowest flow during the installation. That will help you to adjust the place you will install according to the water surface and avoid the skimmer to suck air. Then, if you wish, you can adjust to a higher flow slowly. The outlet of the water is on the bottom of the unit, so that's another reason to have the flow on low in the beginning, to observe the substrate you have on the bottom of the tank. If you put the flow too high and the skimmer is located too close to the substrate, in a low/small tank, for example, you will blow the substrate off! The skimmer doesn't need much flow to operate amazingly! I have it on the lowest flow setting for my 75 gallon tank. It will remove the surface scum in couple of minutes! It's construction is perfect and it works amazingly when installed correctly! The included tweezers is to remove the top grid protection and the blue sponge inside to clean. I am not going to use the skimmer with the included suction cups. I used some cable ties and attached it to magnets. The wire is long!! Very nice! I love this product!! If you follow my instructions in regards to the low flow in the beginning you will not have the micro bubble problem some people observed and complained. One last tip: make sure you aquarium is on constant water level, replacing the evaporated water daily, to make sure the skimmer won't suck air when the water level drops due to the evaporation! This skimmer is one of the very best I've tried, if not the best. Much easier to clean than all the others I've tried! love it!

I got the Crystalskim 350 to help with the surface build up I was experiencing in my 75 gal aquarium. As others have stated, it’s not the easiest thing to set up. It is way too powerful. Even on the lowest speed setting and having the filter as far down in the water as it could go, I still was experiencing micro-bubbles. To solve this, I replaced the provided extremely coarse filter pad with a more fine pad that i cut to size. That solved the issue. Although, i expect this is going to lead to more frequent maintenance. My other complaint is the unit i received is grey, not black. Which is unfortunate because my background is black and i was hoping this would blend in. It doesn’t. Construction seems solid, it is quiet, and it made a visible difference in about 30 min. This is my first Oase product, so only time will tell. So far, it does what it’s supposed to. But since i had to modify a $35 surface skimmer, and i received the wrong color, i’m rating the Oase Crystalskim 350…3 stars. *Edit* The micro-bubbles came back. The only solution I can find is lowering the flow rate all the way down. Which reduced the filter’s effectiveness significantly. The filter is not capable of keeping the surface clean on its lowest setting. So its either a semi-clean surface, or microbubbles. I’m knocking this piece of junk down to 1 star. This is what i get for not getting a Fluval. If the Fluval sk400 was easier to find in America, I would have never went with this hunk of crap in the first place. Avoid this purchase.

Works great. A little learning curve on how deep to place it. Critical device for removing surface biofilm that hinders C02 and oxygen exchange.

Edit- it can suck up the tiniest of shrimplets but have only found one dead one when I opened it to clean out the plant specks. There’s usually a few grazing on the sponge but they are easy to see and I use those handy tweezers that come with it to scoot em off back into the water. Happy with the purchase! (End edit) Built solid, easy to operate and setup. Good quality suction cups and bracket. Very small and compact. Using in a 10gal plantscaped shrimp tank with gravel substrate. Not recommended if you have sand substrates. Excellent with gravels. This is due to the downward water blasting straight down. The intensity of this downwash is based on how + or - you have it set to. My shrimps don’t mind hanging out under it for what it’s worth. I keep it set pretty close to minimum. Silent operation and versatile setup options to best suit your needs. The fine grills seem to be doing a good job keeping my shrimps out but letting the plant specks in (granted it has only been in a day so far but even if they do I’m not worried about em. They’ll be fine till I get to em. Maybe even happy!) I’ll update if anything changes. Note: I did replace the coarse blue sponge it came with for a much finer/denser sponge I cut from an extra foam piece I had from an old filter replacement. I was worried that the insanely difficult to deal with water-meal would be able to go through the sponge holes and go back into the tank. That’s the only mod I did and it’s because I’m using this to fix a problem of water-meal aka pond meal and it’s so much worse than duckweed. Smaller and *far* more prolific. This is making short work of it and for the first time in weeks, I have hope that I can actually beat this “plant” and successfully remove it for good. It’s proven to me to be pretty much the worst. With it taking over a fully stocked, heavily planted shrimp tank, a full breakdown and sterilize was not an option. Manual removal was an proving to be a mammoth exercise in futility. Now that it’s installed, I can’t help but giggle to see the green micro balls of doom get sucked up automatically. I was worried that they would float back up and out and back into the tank when it turns off due to the timer, but it seems the sponge I used traps and hold them perfectly. Rinses off in seconds. I have no qualms with this piece and overall I am super duper happy with this skimmer. It feels quality built and seems like the cost is appropriate. Long story short, This was the answer to a difficult question. “How to remove water-meal in a planted shrimp tank” And boy am I happy I chose this one! I have it on a timer to run for 30 mins every 4 hours. It’s super easy to clean. Just take the top off, use the included tweezers to pull the sponge up and out and rinse off. Easy as pie. No need to turn off, or even remove the unit for this. Great design. It seems like the designer actually knew what they were doing!!! Very rare to see these days. Very refreshing and hope it holds up over time. Super happy to see those micro plants get sucked up. I don’t want to tell you how many hours of my life I wasted with a cup trying to skim these out day after day, clear the surface and the only to find hundreds more the next morning. Literally. This is the way.

This worked to remove the film. I’m rating 3 starts because there is no way to adjust the power. It pushed the bottom current way too strong for my Betta. I have a 10 gallon.