Mistakenly exterminated all invertebrates in my tank

[Geophagus]

Hi,

I inadvertently killed all of my invertebrates. 4 weeks ago I purchased a complete established reef system, a 30 gallon innovative marine tank with a kenya tree colony. I was a freshwater keeper for many years keeping mainly geophagus and other south american fish. This is my first time keeping a reef. After the move ammonia did not spike, the biological colony didn't seem to skip a beat. I test my perimeters weekly and I haven't observed any shift out of the norm for my water. I have been doing weekly 25 percent water changes, mixing my saltwater over night, using a heater, testing the PH and salinity (obviously) before adding the batch to my tank, doing everything I can to avoid disaster. The current perimeters are as follows:
8.2 ph
0.023 specific gravity
0 ppm ammonia
0 ppm nitrite
5 ppm nitrate
75 degrees Fahrenheit
I think my flow is medium, I have a hydor 425 gph nano powerhead and the tank is 36 inches wide.
I have a kessil a150we 6000K on the tank for 6 hours a day.

Everything was going fine until last Saturday, I did my usual 25 percent water change in the morning, and the corals just didn't open up all day, I thought maybe they were being grumpy about the procedure. However, they never opened back up. The next day my fish, a clownfish (CB), a lemon damsel (WC), and a sixline wrasse (WC), started tp exhibit mild signs of aggression which I had not seen before. My longspine urchin began dropping spines. I sensed something was very wrong. Up until now, and this is my theory for what my mistake was, I have been using water from my RO unit, but I wasn't re-mineralizing the water. I believe I poisoned my entire tank with water which was too soft. I immediately did a 50 percent water change using de-chorinated tap water, which is fairly hard (I live in chicago), the fish seem less agitated now, but all the coral is dying, some are turning black, which I promptly remove, the urchin is still dropping spines, suffering, slowly dying in the corner of the tank. My remineralizer is still in the mail, it was delayed somehow due to covid-19, I also ordered a hardness test kit which I realized all too late I was missing from my test arsenal, it should be here in a day or two. I feel like I am trapped and have to watch these poor animals suffer under my care, I am so upset and have been taking it really hard. Do you think my hunch is correct? I will know for sure just how soft the water is when I receive my test kit, and will follow up with those numbers. Could this be anything else? Do I need to raise the salinity? Do I need to somehow add calcium? Do I need more flow for the coral? Is there any chance of recovery? I really need guidance. I feel like a complete failure to my animals. Please let me know what you would do from here. Thank you in advance.

 

[Sniperhank]

I'm not sure what a remineralizer is, but things are pretty easy to solve in saltwater without equipment in general. Large water changes with ro/di water. Most likely things were stirred up and the parameters are out of whack, even though the tests aren't showing anything. The entry level test kits in this hobby are basically junk and only good enough for cycling a tank.

 

[okapizebra]

You don't need to remineralize your RO water. When you mix your salt in you are doing just that. If you are just topping off, straight RO is exactly what you want. It will not impact the pH of your tank.

 

[Sniperhank]

You don't need to remineralize your RO water. When you mix your salt in you are doing just that. If you are just topping off, straight RO is exactly what you want. It will not impact the pH of your tank.

A very good point, especially with pH. pH is one of the most dangerous parameter in this hobby IMO. People see that their tank should be at this number, but test and it isn't even close...they start dosing and crash their tank due to not understanding how pH swings throughout day.

 

[Geophagus]

What do you guys suggest I do? I did a 50 percent water change today using RO water, I apologize for panicking, I don't understand why the system didn't go into shock right away and instead took several weeks to react, I lost almost all of the coral and the urchin, the fish seem fine still as do the hermit crabs. I am just going to keep up my regiment, I read on a forum that I needed to remineralize RO water, I assumed the reef salt mix and PH buffer I was using before were doing that already but was doubting myself. Glad to hear I wasn't directly causing the demise of the life thru that. I guess all I can do is try to provide stability and hopefully the tank will recover and I can start from scratch. It was really heartbreaking to watch so many things die. I pulled all of them from the tank to prevent a nitrate spike. Any advice to a beginner is more than welcome.

 

[Sniperhank]

Stop adding anything to the tank. Just do water changes with the ro/di water. That's it. There is no need to dose anything to the tank. There is a chance that your pH buffer is the cause of your issue here...it is not uncommon for people to chase the 'perfect pH', not understanding that it fluctuates during the day, and crashes it.

So, do a handful of more large water changes. Do one every other day. That will give you pristine water in your tank and level everything to the place where they need to be. Then just monitor. At this point the damage is done and we will finish up some triage so you can go on to have a successful system.

As for wherever you read about remineralizing ro water...that isn't a saltwater thing.

 

[okapizebra]

I agree with the above. If you are worried your pH is too low, aim some powerheads towards the surface to increase gas exchange. This helps gas out CO2 and increase the pH naturally. No need for buffers.

 

[Geophagus]

I have never used buffer before in my freshwater aquariums for the same reason. For some reason I thought this was different & that the creatures in this tank were more sensitive to their surroundings but I now see I was foolish. I will do a large water change every other day using only salt. I have been topping off with pure RO water since setup when water evaporates so I will continue that as usual. Hopefully I can still save what’s left and start from scratch. Thank you.

 

[Sniperhank]

That sounds like a good plan. I'd only do that for a week. Water changes are a good thing, but even too much of a good thing can be harmful too. That is why one shouldn't do more than a 50% water change in one sitting. Shock is still shock.

Either way, you are back on the path for success. You'll be alright.

 

[wmullis0]

Salinity good? Take to a reef store or someone else to check it. Reefs are 78 degrees. I just got back in hobby, acquired 2 hydrometers… one of them was 3-4 points off. Salinity was at 1.041,,,, test aren’t always right.