What the heck are these on my glass?
 

First thing I do every morning is look at my 29g cube tank to see how things are (and sometimes Plectranthias Inermis is still out front hunting, before heading back into the rocks to hide for the day, so I get to see him).

Anyway, this morning I found these flat white blobs all over the upper left front and side walls. After I stopped freaking, I spent about 2 hours on the web looking at pictures but couldn't turn up anything that matches. One of my turbo snails and one fighting conch were in the area. I have seen one or two of these blobs scattered here and there before, and took them off with my mag float when I cleaned the glass.

The cross-section of these things is hard to see, but looks like it's very flat, with a slight raised area in about the middle. I estimate there are about 100 of them and they don't seem to be moving. I've used a sharpie to mark the locations of a couple of them, so I'll see if they move slowly or not at all.

The closeup shows the shape, which is what I haven't been able to match in any of the pictures I've seen. I've combed through online ID guides, nothing there either.

Tested last night, and calcium was 420, mag was 1210, alk was 11.3 (story here: I started dosing with polyplabs One, four days ago after testing params and having them in balance - now alk is out of whack, going to rebalance gradually over the coming week).

Thoughts? Advice? Should I be getting a giant tote of saltwater ready to rescue everything?

Heres a great "critter" guide
http://www.lionfishlair.com/hitchhiker.shtml

Kind of look like what their listing as "pumpkin flatworms" perhaps?

Those are definitely flatworms. They will move, but some species are much more active than others. I'm not sure which species you have - some are predatory mainly to corals, some are prone to plague-like population explosions, and some are harmless. First things first, I'd check very closely that there aren't any on your corals. I'f the corals are clear, I'd keep an eye on their population, and if everything seems ok I'd just ignore them. Of the harmless flatworms, their population will wane and flux, and under normal conditions they aren't usually a problem. If they are on your corals, that's an entirely different matter. If you're noticing their population increasing quickly, that's a different matter too. If they are quite tiny - like 2 mm or so, then they are probably one of the harmless types, though I've had one occasion where a tiny type was infecting a Brain Coral (nothing else). I gave it a couple dips a week apart, and didn't see them again.

how big are they, best bet is to just continuously siphon them out as much as you can with every water change

Add a wrasse, like a yellow/canary wrasse for biological control of flatworms.

+1 for the wrasse. Ive had great success with both my Hawaiian 8 line and my Melenurus. 6 lines may also be good and better suited to your tank size, but I cant attest to them.

Pumpkin flatworms might be it...
 

Thx for that - I checked it out and I think you are right about the pumpkin flatworms. The photos showed them on corals and I don't see that in my tank - yet.

The Feeding Pipette of Death for flatworm control
 

Thank you for the heads-up - I scrutinized all of my corals really carefully, even using the nanoscope and I don't - so far - see anything on them. My bubble coral has been struggling lately and I noticed a few kind of spots on it, but can't match that up with what I see on the glass. I plan to look into whether it's safe to dip the bubble coral and see if anything nasty is shed.

As for size, they are about 2mm in "diameter" and a light pink colour in the brighter light.

On day one, I decided to remove them manually using a feeding pipette (thank you, Canada Corals!). I put tap water into a container to squirt them into, and suctioned them off one by one, getting as many as I could see. They did move when prodded with the tip of the pipette. They were mainly concentrated in the upper left front corner and side wall, and widely scattered when it got to be more than six inches from the corner. So I feel like I got the majority of them - didn't see any of them anywhere outside about a ten-inch distance from that corner.

On day two, they reappeared but this time there were a lot fewer and it didn't take long to remove them.

Day three was today, and I estimate there were only 20 or so.

So we will see what tomorrow brings.

Sucked those suckers off the glass
 

Thank you for this - I decided to manually remove as many as possible. Tomorrow will be the fourth day from when they first appeared and I'm hoping the numbers will be even further reduced.

Will check out wrasses
 

Thanks for the suggestion - I might just check into that. At the moment I have a yellow tail blue damsel who is a jerk. The yellow clown goby perches in the acros to stay safe, the Pygmy hawkfish just minds his own business during the daylight and hunts at night, and the lawnmower Blenny is a lot bigger than the damsel, and actually chased him out of a cave. I'm not sure how the damsel would be with a wrasse and I'm also thinking at the moment I'm fully stocked.

I'll see how things go with the manual removal and take it from there.

Thanks to everyone for the replies - it's great to know there's help out there! 😄