Tank issues post COVID

[Jarad]

As my tank is at the office, during COVID we were slammed, and so maintenance took a bit of a back seat to all things COVID related. However, during that time some really strange things have been happening and I'm trying not to rush to any judgements on cause. My main maintenance was a weekly water change, floss filter changes every 3-5 days, and pump maintenance every 3-6 months. Water changes were pushed some and done as often as possible (maybe every 1-2 weeks), but haven't stopped. However, during this period all of my zoas closed, all of them retracted, and most have entirely melted off by now. My metallic green mushrooms and rhodactis seem fine, but have been sliming (or making cobwebs) every day. My anemone split but is otherwise fine. My scoly hascome off it's skeleton some, but is as bubbly and colorful as ever, so while I'm worried about the detachment from the skeleton it seems ok. My two cleaner shrimp and any pods died off (coincidence?), but hermits, urchins and snails seem unaffected. And all fish seem normal and healthy.

So I'm trying to figure out what has changed and is going on. There is some dinos in the sandbed that started after all the zoas were largely lost (thought it was cyano, but seems dinos are a better fit), and my coraline largely has gone away. Not much else to signal an issue, and I didn't want to jump to any conclusions, so was hoping for your thoughts on what might be going on. I run a UV, tunze skimmer, chemi-pure elite (not regenerated), in a 45 gallon tank. Pic attached if helpful, and would appreciate any thoughts.

Temp - 77-78
Salinity - 35
Alk - 6.6 (hanna) (day before a water change, but has dropped from it's regular 7.5 range where it usually hovers). I dont dose.
Nitrate - 8 (pre covid was around 2, and have been monitoring a slow rise since every month)
Phosphate - 0.17 (hanna) - Only started testing this, but has been .15 and .17 in past two weeks.
Ammonia - 0
Calcium - 441 (hanna)

 

[Rickdareefa]

For starters i would blow everything off with a Turkey baster and a large water change. Try to get the alk close to 8dkh. Looks like you may have some coraline growth hard to tell in the pick but that will start soaking up some calc and alk. Also need to get phosphate down but the large water change should help. I would blow off the rocks do a 50% water change then test the parameters agian and adjust accordingly.

 

[Rickdareefa]

Also looks like a cyano outbreak. Are you using rodi water? Possible excess silicates in top off water could contribute to that.

 

[bluesy1213]

Check your source water for phosphate. I recently had to add a second DI resin to my RODI setup to stop TDS and Phosphate both. I was only using a 4 stage and it wasn’t good enough. Or it could have been a while since your last RODI filter change. Just a thought.

 

[Jarad]

Thanks all. Will check the RO DI source water just in case (should I mix with slat prior to test given the Hanna checker is built for marine water?). Comically, we use commercial grade RODI here at the office, so I know it's kept in good condition, but I'll check none the less. Water change is already set for today, and I suck off all the top layer of material, then stir it up and continue the siphon from there. I thought cyano as well, but it laughed at the Red slime remover. Maybe it needs another dose, but when nothing happened I was hesistant to go further. It also looks like dinos under a microscope as well, so I assumed that as well post slime remover. Thanks for the comments, and I'll see what happens.

 

[Steve Burton]

I was using RODI water to cycle some dry rock in a tote and kept getting high phosphate readings way longer than I thought reasonable. Doing some research i found some believe the phosphate tests hobbyists use are totally unreliable in RODI water, giving false high readings. I'm not sure if this is true, but when I switched to salt water in the tote the phosphate readings went down immediately. Perhaps @ActiveAngel or @ichthyoid could shed some light.

 

[ActiveAngel]

Hmm... I’m not sure about phosphate tests and RODI.

Your Alk is definitely very low. This is the issue of greatest concern given the information. I personally consider even your usual 7.5 dkh to be in the ‘yellow alert’ zone, and would recommend getting it at least up to 8.0 dkH and no greater than 9.5.

The purpose of Alkalinity is to buffer against changes in pH. If your water became slightly too acidic, it could potentially cause all the issues you mentioned.

 

[Jarad]

Great, I'll take a look at that as well in terms of dosing recipe 2 or something similar.