Need help with Diatoms?

[Kozman61]

My tank has what seems to be a Diatom issue. It's a 40 gallon breeder, a few fish and corals that's about 10 months running. I have a Seachem 110 HOB filter, good flow and fluval marine 3.0 lights. It started around mid November with a diatom bloom, looks like brown sugar sprinkled on the sand. My numbers seem to be stable, salt 1.025, ph 8.1 , nitrate 6, phos .03, kh 10.20, Calcium 425 , mag 1300. Weekly 10 to 15 percent water changes but still can't get rid of the diatoms since mid November. I do water changes with Natures Ocean Nutri Seawater and top off with RO water. Light are on 6 to 8 hours with whites at 20 percent max. I tried lights with blues only for 2 days and it's still there. . I also tried chemi clean but it did nothing. Please advise what I'm doing wrong, pics attached

 

[Kozman61]

Anyone?, please help. I've always heard diatoms last a few weeks and disappear. How can I still have diatoms going on 3 months??, is it not Diatoms, maybe something else...is my tank re-cycling?, . I added a sizable dry rock scape in October, maybe it kicked off a new cycle?

 

[griss]

I've never (knock on wood) had to deal with diatoms or dinos but, I believe, @kharmaguru has some knowledge in this.

 

[kharmaguru]

All diatoms need to persist is a continuous source of silicates. What sand did you use for your substrate? Also that premixed saltwater could be a source (just saying, I don't know) and if you are using RO and not RODI this could also be a source.

 

[OldReefGuy]

doesnt add up....even with the WC you do, you also have a GHA issue...

 

[Kozman61]

The sand i don't remember, it was almost 10 months ago.The premix stuff is the seawater in the 4.4 gallon jugs from LFS sell(Natures Ocean) and I misspoke, i use RODI not RO, I tested TDS usually 0 or rarely 1ppm

 

[Kozman61]

Yes I have noticed the GHA also, are my lights an issue?, I only have the whites at 20% max, the blues, purple, cyan are 75-80%.

 

[kharmaguru]

The sand i don't remember, it was almost 10 months ago.The premix stuff is the seawater in the 4.4 gallon jugs from LFS sell(Natures Ocean) and I misspoke, i use RODI not RO, I tested TDS usually 0 or rarely 1ppm

But it was sand intended for reef tanks correct? Construction sand for instance can be literally pure silica.

Yes I have noticed the GHA also, are my lights an issue?, I only have the whites at 20% max, the blues, purple, cyan are 75-80%.

Marine specific lights are never really an issue especially at only 6-8 hours. If you are getting direct sunlight on the tank that can be problematic but you also need nutrients to feed said algae as I think @OldReefGuy is alluding to. I don't see any snails, what kind and quantity of CUC do you have?

 

[Kozman61]

it was definitely sand for a reef tank, not sand box/construction sand. I have no direct sunlight, I have about 5 Nassarius snails, a few Cerith snails, and a sand shifting star fish. I guess I should up the number of CUC, any suggestions of CUC?

 

[OldReefGuy]

Get some astrea and trochus snails.

 

[Kozman61]

Do you thing the rock scape I added in October is causing the issue, I think maybe the rock wasn't cured enough, it may have left it in a bucket for only 48 hours...yikes

 

[griss]

What kind of rock did you use?

 

[Kozman61]

It was a hand made one piece cement arch thing, not the white dry rock or live rock. Here's a pic when first put in tank in Oct.

 

[griss]

Interesting, where did you get it from? I wonder if it is leaching silicates and/or something else that's contributing to the algae?

 

[T Diddy]

Handmade rock work is typically just Portland cement and aragonite/shells. If any sand (play sand) was used, that could be leaching silicates and causing the problem

 

[griss]

Handmade rock work is typically just Portland cement and aragonite/shells. If any sand (play sand) was used, that could be leaching silicates and causing the problem

Exactly, that's why I was asking where it came from. I've made rocks just like you mention in the past.

My thought process was, if the OP didn't make it themselves and it didn't come from a reputable manufacturer, who knows what could be in it.

 

[T Diddy]

Exactly, that's why I was asking where it came from. I've made rocks just like you mention in the past.

My thought process was, if the OP didn't make it themselves and it didn't come from a reputable manufacturer, who knows what could be in it.

Hah! Jimmy Hoffa could be in there!

 

[OldReefGuy]

Portland Cement also contains silica albeit typically 1 - 1.5% by vol.)

 

[griss]

Portland Cement also contains silica albeit typically 1 - 1.5% by vol.)

Learn something new everyday

 

[Kozman61]

I guess I should test the water for silicates?