Rusty dots on Substrate - Please help ID

[dhof]

I have rust/red colored dots on my substrate for about 4 weeks now. I need help badly in figuring out what these might be. I took the time to make a long post so there was enough information for everyone (sorry about the length)

TANK BACKGROUND:

1. I have a very well stocked LPS/SPS Fluval Evo 12.5 with 4 fish, which is 7 months old
2. I run very stable parameters in spec with Randy's article for acceptable reef tank values. I have a Neptune Apex, and I dose 2 part. I hand measure Alk/Cal,Mg/Phos/Nitrate every day and keep things pretty stable. For example, today is 1320Mg, 9.0Alk, 460Cal, 0.03phos, 2ppm Nitrate, which is pretty typical.
3. I do not recall having any 'diatom bloom' when cycling my tank, but I had a ton of ugly phases with green hair algae. Nothing ever brown or red, only green uglies.
   
4. I had been performing 50% water changes for the past few months every week. Prior to that I had been performing 20% water changes every week. I was doing 50% only because it is so easy and I figured it wouldn't hurt anything. I have a 6 stage RODI which produces 0 TDS by the built in meter and a handheld meter both.
5. One weird occurrence over the past 3 weeks that I will note is that my lighting starts to ramp up at 12:30pm until full light at 4:30. All of my corals open up at 12:30 and look great until 3pm when every single one of them retract for about an hour or two. Zoas close, GSP closes, montipora spongodes polyps retract, hammers and torches retract, bubble retracts, hairy mushroom retracts, basically everything. Around 6 or 7 pm all of the corals open up again. I do believe this is related to the rust colored dots in some way because it never happened before (I have a webcam on the tank and watch it throughout the day)

RUST COLORED DOTS BACKGROUND:

1. About 4 weeks ago, a 'dusting' of rust/red dots formed on top of my substrate.
2. The Rusty dots are not on my live rocks at all, only on the substrate.
3. It is not 'slimy', nor does it form into long hairs, it really reminds me of a powder more than anything.
4. It is disturbed quite easily with a baster or any manual stirring of the substrate, resulting in 'clean' looking substrate pretty easily. The 'clean' disturbed portion will remain clean for over 24 hrs before becoming rust dots again.
5. There are no perceivable air bubbles forming on, or around, the rusty looking dots on the substrate.
6. The rusty colored dots are present on the substrate whether day or night. Overnight with the light off, the rust colored substrate covering looks identical to when the lights are on.
7. I am not having any snails dying or acting strangely whatsoever (although my snails have always been pretty lazy).
8. I can vacuum the substrate out completely, but the rust colored coating will return in 24-48 hours. Repeating vacuuming delays another 24-48 hours but it always seems to come back. Incidentally if I just leave the substrate be, the rust colored coating just seems to get to a certain point and doesn't really get any worse.

MICROSCOPE AND PICTURES:

1. I borrowed a very nice microscope and took 4 different samples from the tank substrate in various parts of the tank. I prepared 6 different slides with various stuff I could capture with an eye dropper from the samples. Each slide has 3 separate slide covers on it. I've looked at a few thousand of these rust colored dots in solution under the glass slide covers, outside of the glass slide covers, and on pieces of substrate.
2. I think I might have seen 1 or 2 of them move, but I really can't say for certain whether they were in a water bubble current or if they actually moved on their own.
3. The thousands of other rust colored dots are completely motionless, and I can stare at them for hours without seeing any form of movement. I take the sample of substrate directly to the microscope and it is less than a minute before I am viewing the slide. Of course I see transparent bugs like coepepods and things like that moving, but no movement to speak of on the rust colored dots. Not even any sort of vibration on the rust colored dots.

ASSESSMENT/QUESTIONS:

1. I realize these look a heck-of-a-lot like dinoflagellates. The lack of any sort of movement, that they are not 'slimy', and that they don't go away at night make me think maybe they are something else.
2. I have seen some examples of circular diatoms, but it sounds like those are pretty rare in the aquarium.

Above: 40x magnification. The outer edge of these things seems pretty in-tact

Above: another 40x shot

Above: a 40x shot of 3 rust dots in free standing water (not under a slide cover) none of them are moving or vibrating at all.

Above: 10x view of some rust colored dots

Above: 10x view of some rust colored dots and what I think is some algae. Again, nothing is moving or vibrating at all. No motion. Some of the red dots appear to have white areas through the middle.

Above: 40x view

Above: 40x view

Above: a collection of rust colored dots. None are moving at all, and some sort of spiny clear thing in the way horizontally.

Above: 100x magnification

Above: 10x magnification of a collection of rust colored dots. None move or vibrate whatsoever, they just sit motionless

Above: 40x magnification of one of the rust colored dots

Above: Rust colored dots on substrate. These things are really on the substrate rocks a lot. To get them in the free fluid water for the slides I sometimes have to really agitate the substrate to be able to see anything.

Above: Rust colored dots on substrate in the tank

Above: Rust colored dots on substrate using a cheap microscope.

Thank you in advance if you have any help whatsoever!

 

[1WildBill]

Sounds like diatoms to me, maybe someone else will chime in with their opinion. I’ve never seen diatoms under a microscope. How log has the tank been cycled?

 

[sp4zzy]

I'd second diatoms - hard to say for sure based on the microscope images as they come in several shapes and sizes. The tank picture and description fits with my experience though.

 

[dhof]

I'd second diatoms - hard to say for sure based on the microscope images as they come in several shapes and sizes. The tank picture and description fits with my experience though.

Sounds like diatoms to me, maybe someone else will chime in with their opinion. I’ve never seen diatoms under a microscope. How log has the tank been cycled?

Guys, thanks for your opinions. You don't know how relieved that would make me if they really are diatoms. I'm stressed thinking they might be the dreaded dinoflagellates, so your opinions are really helping me relieve the stress. If I get enough more opinions in the diatoms front, maybe it'd save me from having to read that darn dino thread that has like 4000 posts

Tank has been cycled for about 6 months. I used the BRS Reef saver and I have coral substrate.

 

[MannyT]

I’m having something similar on my sand, the only difference is that it only appears when my lights are fully on and goes away when they’re off. Is that still diatoms? Tank is about 5 months

 

[SaltyGroves]

Wow you really did a great job with the microscope pictures[emoji1303]This is very interesting, following!

 

[dhof]

I’m having something similar on my sand, the only difference is that it only appears when my lights are fully on and goes away when they’re off. Is that still diatoms? Tank is about 5 months

Manny, I am no expert, however your symptoms where things appear under lights and disappear when lights are off sounds like a classic symptom of dinoflagellates. My understanding is that dinoflagellates have a little tail that they use to accelerate and move about, and that may be how they come to the surface for light and go away in the dark. Others can weigh in, but your symptoms sound different than the one I started this thread with and you probably should take a look at the monster thread "Dinoflagellates, are you tired of battling them alltogether" which is stickied in this forum.

 

[MannyT]

Manny, I am no expert, however your symptoms where things appear under lights and disappear when lights are off sounds like a classic symptom of dinoflagellates. My understanding is that dinoflagellates have a little tail that they use to accelerate and move about, and that may be how they come to the surface for light and go away in the dark. Others can weigh in, but your symptoms sound different than the one I started this thread with and you probably should take a look at the monster thread "Dinoflagellates, are you tired of battling them alltogether" which is stickied in this forum.

Thanks for the reply. This is what I’ve been scared of hearing.

 

[dhof]

Just an update. After I posted this thread, I continued to just do my normal tank maintenance, stirring up the substrate every few days to get the rust dusting on the substrate to go away. I did change to doing 20% water changes instead of 50% because I thought maybe the large volume water changes might have been introducing more silicates. Then one day a few weeks after this post, the rusty dots in the substrate basically stopped coming back the next day. Somehow within a week they basically all went away, going from horrible to not existent. This was about 7 or 8 weeks after they first showed up.

I have to conclude that they were, in fact, diatoms. Thought I'd wrap this up for whomever might see the thread and has similar things appearing.

Thanks,

 

[Lowefx]

Just an update. After I posted this thread, I continued to just do my normal tank maintenance, stirring up the substrate every few days to get the rust dusting on the substrate to go away. I did change to doing 20% water changes instead of 50% because I thought maybe the large volume water changes might have been introducing more silicates. Then one day a few weeks after this post, the rusty dots in the substrate basically stopped coming back the next day. Somehow within a week they basically all went away, going from horrible to not existent. This was about 7 or 8 weeks after they first showed up.

I have to conclude that they were, in fact, diatoms. Thought I'd wrap this up for whomever might see the thread and has similar things appearing.

Thanks,

I am currently having the same issue. What did you change to overcome these? Change any RO/DI resin? Change any lighing or time frames?

 

[1WildBill]

How olds your tank Lowe?

 

[Lowefx]

How olds your tank Lowe?

Almost 3 years old, with one move to the new house a year ago (i tranferred all rock and 40g water) its a 120g. My theory is that it is silicates and my ro/di needs a booster pump or replaced carbon, but theyre only 6months old.

 

[dhof]

I am currently having the same issue. What did you change to overcome these? Change any RO/DI resin? Change any lighing or time frames?

I spent a lot of time in the microscope trying to characterize these things. It seemed most plausible that they were Diatoms because nothing was moving around at all. By the time i posted this thread (4 weeks) I was feeling pretty desperate. The users here seemed to confirm the diatoms ID, so I figured that waiting it out might help. Here's an anecdotal list of some of the things I did do in the last 3 weeks of my issue, but I suspect none of them really contributed significantly to these things clearing up more than just time:

1. My Nitrates were zero, so I did start dosing sodium nitrate to 2ppm.
2. I stirred the substrate (really, I water-jetted it with a feeding baster tube) every few days.
3. Previously, I was doing 50% water changes every week, and I changed it to 20% water changes weekly.
4. I changed my salt mix from Aquavitro Salinity to Red Sea Coral Pro.
5. My RODI source was the same stock water from a 44G brute through the entire 7 weeks, I did not make any new RODI from the beginning to end, just used the same water from the same brute.
6. My 6-stage RODI is pretty new so I've only changed the 1st stage and the DI resin once previous to this event.
7. I did order a Salifert Silicate test kit (I really think silicates must've been the problem), but by the time I received the test kit, everything cleared up so I still haven't tested my RODI yet.

Thanks,

 

[1WildBill]

Do you have a TDS meter on your RO/DI? If not, I would suggest one. They won’t help with diatoms, but it’s nice to know when you really need to change the filters? Can you post a pic of your tank?

 

[dhof]

Do you have a TDS meter on your RO/DI? If not, I would suggest one. They won’t help with diatoms, but it’s nice to know when you really need to change the filters? Can you post a pic of your tank?

I think WildBill might have been asking this question of Lowefx, but wasn't entirely sure, so I'll answer anyway.

I do have the triple TDS meter on my 6-stage RODI and monitor that for when to change various filters in the RODI unit. I did just test my silicate since my last post (first time testing Silicate) and it was zero.

Here's a video I did of my tank at 6 months:

 

[1WildBill]

Yes I was. Sorry to hijack. Beautiful tank BTW.

 

[Lowefx]

Do you have a TDS meter on your RO/DI? If not, I would suggest one. They won’t help with diatoms, but it’s nice to know when you really need to change the filters? Can you post a pic of your tank?

Yes i do have one. Ill test it later and also post a picture of my issue and tank

 

[Lowefx]

TDS reads 000

 

[Lninwa]

I think WildBill might have been asking this question of Lowefx, but wasn't entirely sure, so I'll answer anyway.

I do have the triple TDS meter on my 6-stage RODI and monitor that for when to change various filters in the RODI unit. I did just test my silicate since my last post (first time testing Silicate) and it was zero.

Here's a video I did of my tank at 6 months:

Beautiful tank!!

 

[Lowefx]

I think WildBill might have been asking this question of Lowefx, but wasn't entirely sure, so I'll answer anyway.

I do have the triple TDS meter on my 6-stage RODI and monitor that for when to change various filters in the RODI unit. I did just test my silicate since my last post (first time testing Silicate) and it was zero.

Here's a video I did of my tank at 6 months:

Any ideas?