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What kind of algae is this and how do I get rid of it>

1153 Views 5 Replies 3 Participants Last post by  schmuttis

We recently had to remove all of the fish and plants from our tank (for about 4 days) while we replaced the top frame. When we moved the fish back into the tank we used the water from the fishes temporary tank (the plants were in another tank).

About a week after putting the plants and fish back in the tank we started with this problem:

A slimy algae is all over the tank and seems to doubling in size each time we look.

Tank specifics:
120 gallons - 5' long (2 built-in overflows on back sides)
high lighting:
4 T5 power compacts - 54 watts each
2 halides - 250 watts each
photo period:
power compacts - 12 hours
halides - 10 hours
CO2 injection controlled by PH - 6.9
constant dripping water changes - soft, acidic well water
substrate - EcoComplete (we added 20 lbs the day before we replaced the plants)
20 - 30% water changes usually every week to 1 1/2 week
tank temperature - 84 degrees F (heaters and chiller)
animals: 6 discus, 72 other fish (tetras and oto cats) and 4 Amano shrimp
EI fertilization:
KNO3 - 11.5 PPM added every other day
KH2PO4 - 1.955 PPM every other day
CSM + B - added on alternate days
sump: bioballs, mangroves (light on at night), mechanical filter pad and sponge
we kept water flowing over the bioballs during the tank repair
I add about 6-7 tsp. of baking soda per water change for the KH.

This is what the tank looked like before we took it apart:

What would you suggest that we do and what type of algae is this?

Thanks for your help.
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Additional information:

We are also dosing with FE along with the trace elements.

We are doing a 50% water change. We bottle brushed and sucked out as much of the algae as we could.

Our tank test readings are:

Ammonia - 0
Nitrite - 0
Nitrate - 30
Phosphate - 3.0
Iron - 0.32
KH - 4
GH - 4
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We've been putting in Algae Destroyer Advanced (Aquarium Pharmaceuticals) every three days and have been using a bottle brush to pull out the slime. This is keeping the algae under control but not eliminating it. We're still looking for suggestions if anyone has any idea what this is or how to get rid of it.
This is an awesome algae guide:

Looks like you may have Rhizoclonium.

I'd cut your lighting WAY down (even the T5's alone I think might be enough, at least for now) and drop your light period to 8 hours or less, at least until this is all under control.
I agree with rich, that is an insane amount of light. Seems like you have mostly medium to lower light plants. I am also sure that the discus would also be happier with less than half of the amount of light that you are using.

Most planted tank people are now cutting there photo periods to 8 hours. I have done this and it works great.

Are you using a drop checker for CO2 detection. It sounds to me like a normal pH for kH=4 water is around 7.0. With 30ppm of CO2 it should be around 6.0. There are other things that complicate the equation so a drop checker with 4dkH is really the only way to tell. Also using a sump with bioballs IMO will degas any CO2 that you get in the water through a diffusor or a reactor.

I would also try and stop using the Algae Destroyer if possible as this will not fix the main issues in your tank and I don't like to add chemicals if at all possible. Fluorish Excel seems to have some pretty good algicidal effects and less harmful to the tank inhabitants. I don't have any experience with it and your particular type of algae but it does work for a few others.

Hope this helps.
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Thanks for the advice - it's greatly appreciated.

The algae definitely looks like Rhizoclonium and I'll take your advice and turn off the halides, cut the T5s to 8 hours and pick up some Excel.

It's hard to believe that we could be short of nutrients or CO2. Before we had to take the tank apart the plants were looking quite happy (see the bottom picture) and we haven't changed the dosing, lighting or CO2. We keep the kH about 4.5 and the CO2 is controlled by pH which we have set at 6.8/6.9.

While the plants were in their temporary tank, they were just floating in water and did not get dosed. The only lighting they had at that point was a shop light with 2 regular florescent bulbs above them. I'm thinking perhaps I should have gradually increased the lighting once they were planted again.
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