Rust color algae problem

I've tried numerous things to get rid of this rust colored algae on the white sand. I've done practically complete water changes several times. I've changed every filter in my Rodi unit. I've changed filters all together. I've reduced lighting. I've reduced the how much I'm feeding the fish. While nothing seems to be dying in the aquarium, including the corals, I don't know what else to do to get rid of this. Few weeks ago I use the red slime remover and while that seemed to work for the immediate time, everything came back. I even removed 80% of the rock work thinking that this would dramatically help. I vacuumed the sand each time I do a water change as well.

In my opinion I've done an awful lot I try to eradicate this issue. While my RDI unit has a meter to check the water going in and out my test kits for the saltwater aquarium have expired and I need a new one. Other than the kit that I need to buy, I'd rather not for a bunch of money at it and try to get an opinion or two from the community as to why this continues to be a problem. Thanks for your help in advance.

Also, I'm running an oversized skimmer in my 37 gallon, as well as filter with carbon and GFO. I have the return of the filter creating a gyre that's visible.

 

This is the biggest part of your problem. By using a red slime remover, you killed off the algae, but since the underlying conditions were not corrected, the algae simple regrew, and possibly this is a type that will be a lot harder to get rid of.

From the picture, it looks like your tank is fairly new. It's not unusual for a tank to go through several algae blooms like this in it's first year of operation. Often the best thing to do is let this run it's course, and just keep cleaning things for awhile. Above all don't panic and make a lot of changes with out carefully thinking them out.

I have posted this before, and it's a summary on algae control.

DaveK's Standard Lecture #2 - Algae Control

Algae control comes down to controlling nitrates and phosphates. If you have a problem with algae it is because these two nutrients are out of control. Do not think that just because your test kits read zero or low values that you do not have a problem. In many cases the algae is removing the nutrients and growing. This is why there is a problem.

Here are possible sources of nitrates and phosphates -

Feeding, especially flake food and not rinsing frozen foods before feeding.
Using tap water to mix salt. Always use RO/DI water for this.
"Dirt traps" and "nitrate factories" in the system.
Low quality carbon can leach nutrients.
Low quality salt can sometimes add nutrients. This is unusual today.
Livestock load on the system

Here are possible ways to remove nitrates and phosphates -

Water changes. Change 1/2 the water and you reduce the nutrients by 1/2.
Skimming. Remove the waste products before the biological filtration need to break then down.
Nitrate and phosphate removal products.
Deep sand beds.
Refugiums.
Algae Scrubbers.

Each of these has advantages and disadvantages. Most people that control algae will use many of the above methods.

There are also other items that can effect algae growth rates.

Good clean up crew.
Other livestock that eats algae.
Low general water quality, especially when the readings are off.
Lighting, sometimes you can reduce it, especially in FO or FOWLR systems.
Old light bulbs. Colors change as they age and this can be a factor.
Water flow. More flow will often help keep algae down.
Manual removal. Very important, especially when there is a big problem.

 

@DaveK
Thanks for your insightful and thorough response. Much appreciated. I understand your message on the approach to eradicating the underlying issue. Your points on being aware of the results of a test kit and how that doesn't necessarily portray the entire picture of what's going on eye-opening. Thank you.

I will begin addressing the issue by performing the water changes as suggested. Next, I will address the food points that you made. Hopefully, that will put me on a better path.

Currently I have one Turbo snail and four astraea snails as well as 4 Nassarius in my clean up crew. What else would you recommend?

 

Adding a clean up crew can do a lot but you still do need to fix the problems that are causing the algae.

There are a lot of ways you can go with a clean up crew. A lot depends upon what fish and other livestock you have in the tank. Most will have several kinds of snails and hermit crabs. Some don't like hermit crabs, so they go with all snails. there is no really right or wrong answer.

Here is a web page from Pacific East Aquaculture, one of our sponsors, of clean up crews they offer. (offsite link) - https://pacificeastaquaculture.com/collections/invert-kits There are other places you can get a good clean up crew from. The thing I want you to notice is that a typical clean up crew has about 1 1/2 snails and/or hermit crabs per gallon of water. This gives you some idea of where you want to end up. One of the nice things able a clean up crew is that you can always add to it later.

BTW, if your in driving distance of Pacific East Aquaculture, the place is definitely worth a visit. See this web page for location, and hours - https://pacificeastaquaculture.com/pages/our-facility It's one of the best places for corals and livestock. I live near Philadelphia and make the long drive from time to time.

 

Thank you Dave. I ordered a bunch more cleanup crew to supplement buy existing Nassarius snails and Astrea snails. I wish I wasn't driving distance of that store, but I'm lucky enough to have a couple close by that I was able to make it out to. I'm doing frequent water changes, and have been doing a lot more tank maintenance lately. I will give an update in a month or so when I've started to see a change. Thanks again.

 

I had the same problem but it was on my display tank glass. I got phosphate remover, specifically phosguard, from Amazon. Check your nitrates and phosphates regularly. I wipe my glass with cloth rags to physically remove the algae from the tank.