Hi I would like to add some information on this type of algae.
My 300 gallon has gone through some changes over the past few years.
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About two years ago has some LFS put copper into main display ... It created a ton of nutrients in the tank which fueled a huge hair algae take over. ...
...This time it was more of this purple/maroon colored slime with bubbles in it.
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The tank according to our mainteance fellow is good.
- Nitrates 10
- Nitrite 0
- Ammon - 0
Ph ?? but normal
Phosphates - a bit high .2?
The tank seems to be a death pit for new fish. They look fine for weeks but they end up gasping for air at top and spining around. We took one in to LFS who said its not ich. 1 week in copper/blue solution seemed to cure it.
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My tank person said that every FO tank he tanks care of that has hippo tangs all have the same problem. The tangs get that beat up look to them, color rubbing off the nose etc. Looks like lateral line disease maybe it is but they live a long time looking beat up. 6 + years.
He has taken some of these tangs and put them into a reef tank, he says they get all their color back.
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Does this plan make sense? Is it insane?
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Ok, as you can see from the edited post your system has a lot of problems. You have an algae problem, a system treated with copper problem, a nitrate problem, a new fish death problem, and possible problems with tangs (not sure if you have this problem with a tang, or are just commenting on why you want a refugium).
Additional notes -
A sea hare will not eat red algae (cyano), very few things will.
A skimmer removing only 1 cup of material a week is way sub standard. I get more than that per day out of the skimmer on my 125 gal tank, although some of this could be due to a low bioload.
The new fish death problem seems to indicate a disease problem. Most likely your existing fish have acquired some immunity to the disease. Because copper seems to work, and the disease doesn't seem to be SW ich, I suspect we are talking about marine velvet here. This is another parasite disease.
I do not think your plan makes sense and at best only applies a band-aid to the underling problems.
The first think I recommend you do is to step back and think about what you want out of your system. This will dictate what you need to do with your existing system.
Here is what I would do if it were my tank. It is a radical approach. In effect this is a conversion to a FOWLR system, which I consider to be much more effective and give much better results compared to a FO system.
I would remove all fish to a quarantine tank and treat then for 8 weeks with the usual copper treatment.
I would remove all inverts to another tank that can hold them for an extended period.
I would tear down the 300 gal tank, discarding all existing sand, if any, and all decoration that may have absorbed copper. This is mostly coral or other coral based rocks.
I would discard the entire existing filtration system. UV unit, skimmer, canister, and all other filter components.
Sterilize the remaining equipment is a bleach solution, rinse and soak in several FW changes.
If the system is not "reef ready", that is having built in overflows, either drill the tank and install internal overflows, or get external overflows. You'll need at least two large ones for a 300 gal tank.
Replace the filtration system with a berlin type sump, and a large powerful external skimmer rated for about a 600 gal tank. (Manufacturers tend to be "extremely optimistic")
You may also wish to include some phos-ban and/or carbon reactors in the filtration system. You may also wish to include a refugium. These are optional and could be added later.
Get all the equipment installed. Then fill the system with fw and test for leaks.
Next, you are going to need biological filtration. Traditionally you would use about 300 lbs of live rock. This would be fine, but would also be very expensive. Alternatives are dry coral base rock or making agrocrete rocks. In any case, you'll need 300 to 400 lbs of rock. I would use just enough sand to cover the bottom.
Drain the FW used to test your system, Refill the system with the new rocks and SW. Make sure you use RO/DI water to mix your salt. Add a few new live rocks to seed the system. Add a raw uncooked deli shrimp to start the initial cycle.
After the initial cycle completes, test your water for nitrates. If you get a high reading for them, either make large partial water changes to reduce them, or wait for the natural processes to lower nitrate. This could take weeks.
Once the fish have been treated for 8 weeks, you can add them and the inverts into the newly setup system, but add them back slowly. Only add 1 major item a week. Give the system time to establish things.
Be sure to quarantine any new livestock additions. You just went through a total rebuild to fix everything. No point in messing it all up by adding a sick fish.
Enjoy your new setup. Feed your tangs a lot of vegetable matter. Nori sheets are a good source. Nori is the seaweed used to make sushi. You can usually find it in a well stocked grocery.
