Sudden brown algae bloom in new tank

[ahochan]

Hi,

I've recently set up a 60 cm tank / 40 cm sump FOWLR tank.
Its been running for around 3 weeks. Two days ago, I suddenly got a major brown algae bloom. I use normal aged tap water, and don't have access to RO/DI water.

I set the tank up by using some live rock from my previous single-fish miniature tank that had been running around 4 months. On that tank I've only had green algae on the tank walls, no brown algae. I also added live sand. I then bought some rather cheap live rock, cured according to the shop.

The new live rock I bought is now all covered in red algae, while the live rock from the old tank has no red algae at all. Does this mean that the new rock I got was bad? The rock was significantly cheaper than the rock I kept in the small tank.

I've not had any ammonia spike yet, and I sort of assumed that the bacteria seeded from the old tank would bring the new tank up to speed without any significant cycle. Now, my test kit gives 1 mg/l NO2 and less than 10 mg/l NO3. ph is around 8 mg/l.

Any ideas on how to get rid of the algae and promote more healthy and pretty algae on the new live rock? Would it be a good idea to move it to the sump for a day or two?

Any ideas on what kind of cleaning crew to get? How many hermit crabs? How many snails? anything else?

Just a small addition. Found this in the algae control article:

Diatoms (dusty, rust colored)

Diatoms are probably the most common form of algae found in aquariums. Every new aquarist finds diatoms in their tank at the end of their cycle. Diatoms are easily controlled through the use of grazing snails. If you find a bloom check out you silicates, as they are incorporated into this algae's shell. These algae can also be hindered through the use of RO/DI water for make up water.

I guess this is the type of algae I have. Could anyone suggest what kind of snail to get for grazing off live rock. There's no algae on the glass yet, just on the live rock and substrate.

 

[austinsdad]

There should be no nitrite. Wondering if some kinda mini cycle did take place after all.

Anyway, the diatoms will pass. Most likely, it's what you have. All new tanks seem to go thru that.

Have you been able to test for phosphates from the tap water - to see if you have any problem there?

Done any water changes yet? Any critters in there?

 

[roka64]

It sounds like the end of a cycle, where the nitrItes are heading down to 0 and the nitrAtes are heading up.

 

[ahochan]

I've done two 5% water changes. One a little more than a week ago, and one just after I discovered the algae bloom yesterday. There's one yellow tailed blue damsel and a small hermit crab in the tank (from my mini tank that I've taken down). I feed sparingly, but I've noticed that he never touches the food once it hits the tank bottom. Would it be helpful to not feed anything for a day or two to kill off the diatoms?

As for testing the tap water, the only test kit I have now is a Tetra strip kit. Haven't gotten around to getting anything more advanced yet.

 

[roka64]

I feed my tank every other day. I'm not sure about that specific test kit. I hear the strips are not as accurate as others.

 

[Kurt_Nelson]

After nitrites go to zero, Trochus snails will take care of those diatoms for you. Drip acclimate them - don't just do the 15 minute "float bag in tank water" trick.

You'll want to get a good liquid test kit. I've found the strips are good for a "quick check", but to really determine where you are in your cycle you'll want a more accurate means.