Sad vent :(

Sparten14235 · May 17, 2026

I need to vent and this post may help newer people like me. I've had a 20g long since mid Feb. Everything was going great. I think i was doing all the right things, taking it slow. I gradually got a lawnmower blenny, a pincushin urchin, 2 clownfish, and a fire shrimp. Everything was stable as much as i could tell and I was thinking of even getting coral soon.

But then I ****** up and everything seems to be going wrong all at the same time. I hate bristleworms. Millipedes make me physically sick to look at. I found a huge one, maybe like 3 to 4 inches 2 weeks ago on the sand bed and I went crazy trying to remove it. I ended up removing all the animals into bowls and I basically removed half the sand bed and sifted through it to remove the worms in there, then I threw out 2 rocks cus large worms had hidden inside it, about 25% of the rock, which i replaced the next day. I remember reading about how stirring up the sand bed could release a bunch of bad stuff but I didn't realize how much, and also how sensitive everything was. I should have slowed down and looked at my options first like traps but I was a moron.

I thought things were okay, then a snail died, then 3 of my 4. Then my urchin started getting bad. I noticed lack of movement, missing spines, no longer climbing walls. I did a large water change, about 40%, replaced the carbon in my filters. It seemed to help. The urchin started moving a fair bit. Then one night the heater stopped working and I found the temp at 70f. I immediately fixed it with a spare heater. It wasn't even the heater working. I was stupid af and kept the heater in the back of my aio cus I didn't like the look and the water evaporated too much and it stopped working i guess at the exact moment where i wouldnt check it for a while. I had never let that happen before, I check the level basically every day.

Then my refractometer came in and I checked it today and my tank is at 1.030. So I just went to the fish store and got rodi water to start lowering the salt level. I was stupid and have only been using saltwater for top offs and water changes for months so I've been making that worse too. The urchin still moves a fair bit but I think its lost about 50% of its spines and I feel horrible. Im trying to stay positive and fix the problems I as I find them but im really upset that I let some worms get to me and i basically destroyed my tank and probably killed my urchin. On the positive side the fish and shrimp are okay i think. To newer people like me, dont react immediately. Take it slow. Any advice for my urchin would be welcome. Thanks for joining my Ted talk <3

W31Olds · May 17, 2026

I would'nt sweat to much about your Urchin or your Snails. Urchins are short - lived and keeping Snails is hit or miss. Everyone loses a few for unknown reasons. I've had entire batches slowly die. Your main concern should be your Lawnmower. They can be tricky to keep long term and need lots of Algae to flourish.

Red_Beard · May 17, 2026

That stinks. I think we all have to go through something like that at sometime or another though, no better teacher than experience. Ihope your tank bounces back!
For the urchin, just keep things as stabile as possible for the next while. Make any changes slowly and try to only make one at a time. You could see if you could supplement the urchins diet if your tank is sparse on algae with some algae wafers or nori. Just dont go overboard with that either. A little goes a long way. You lawnmower might like some too.

mfinn · May 18, 2026

Inverts come and go.

It's a sad part of reef tanks.
Another thing with reef tanks, is get used to seeing bristle worms. They are just part of it. They are part of the cleanup crew.
Work on having rodi water around for topoffs.
Work on the equipment side, like dependable heaters.
Stuff that happens, are lessons. Learn from them.

Hang in there.

exnisstech · May 18, 2026

You would probably be better off with a freshwater tank if you can't take seeing a bristle worm. Sorry but that's JMO. You can't go tearing a tank apart every time you see a worm or you'll never have a stable tank. There are some natural predators like arrow crabs I think but they come with their own risks. I hate to say it but I have 4 tanks running and there are bristle worms in every one. I normally only see them if I move something or come out and look at the tank during the night. I rarely see them other wise but I know they are there.

slogan315 · May 18, 2026

Hang in there! Sounds like you had a relatively low impact lesson learned. If anything, this situation has resulted in you topping off with rodi, purchasing a refractometer, and learning to not overreact! That’s a win, and will result in much more success than having this never happen.