HELP! with flow and filtration

Jeremydb · 2026-08-17T20:22:03-0400

I have a 120 gallon tank that has been setup for about a year now. I have lost 5 fish recently due to water quality and not changing the water as much as I should (Assuming). I have added RO water when salinity was high to maintain it. Changed the water once a month or at least tried to. I want to set this aquarium up right and give it one more try (Before the wife tells me to get rid of it). I've provide pictures of what I have.

Filter: I have a Fluval RX6 canister filter with 4 air lines to the tank.
Flow: Hygger HG042 on opposite end of the filter flow and I have another small fan next to the filter flow to assist.
Lights: two Fluval Aquasky 1200mm lights

I have a phosphate reactor from BRS but have not set it up yet. I noticed my phosphates have grown to almost 1.0 ppm. Thought this would assist with this issue.
I have not gotten a protein skimmer as $$$ is an issue and I do not have a sump setup.

I need some advice on what kind of flow control would you suggest?
Do I need the protein skimmer?
How would you suggest installing the reactor on this setup? I am having a hard time installing things as it seems it requires some custom clips to hold the hoses.
Any suggestions on what I should do (other then more water changes, I know I know) that I'm not doing?
List of fish that died - Yellow tank, blue tank, lemon peel angel, yellow tail chromie, and two snowflake clowns

Mr. Mojo Rising · 2026-08-18T07:14:04-0400

It seems like you don't have an ATO which would be my #1 priority to get, that will solve "needing to add RO water to maintain salinity".

IMO you are light on flow. My 40 breeder has the return plus 2 gyres plus a powerhead behind the rocks. A 120 gallon tank needs more than one powerhead for good flow IMO. There is a whole world of powerheads and gyres so its really hard to suggest something.

Your filtration has no means of exports, nitrates and toxins and organics will build up since their is no exporting type of filtration and no water changes. A skimmer will definitely help in this regard but can you share your water parameters? A sump is not needed for a skimmer, I use hang on back skimmers.

There is no algae in the tank for tangs have you supplemented their diet?