Must be missing something obvious..

Triggerjay · Nov 11, 2015

I have a small 45 gal sps dominated reef. The overall health of my corals has been ok, but not great. I used to do a weekly 10 gal water change. I dose part 2 of two part (oddly Alk never declines) and mag via dosing pump. All parameters are within acceptable ranges for SPS. About two months ago I decided to do a 90% water change. I noticed immediate positive results in color, growth, and PE. I have since modified my routine water changes to the 90% and the tank looks stellar. It's obvious that my system is depleting something or my water quality is declining rapidly and I would like to find out what is going on, but I'm at a loss for ideas. I experimented by going back to a smaller water change one week and noticed that overall talk health just wasn't as stellar as it was with the big water changes. What could I be missing? Maybe some magical ingredient in my salt mix?

Jimmyb819 · Nov 11, 2015

My first thought is that your alk test is bad. I don't know how you could be dropping calc and not alk, the way I understand it you should drop alk first. Your 90% water changes are then giving the corals the alk they need. Just a thought.

Have you verified alk with another test?

Triggerjay · Nov 11, 2015

Yes, NYOS reads 8, Red Sea reads 8. Salt mixes at 8, and tank just prior to WC reads 8. I used to see higher Alk with IO salt, but switched to Red Sea blue bucket about 6 months ago due to a bag of IO mixing at 14DKH.

Jimmyb819 · Nov 11, 2015

Triggerjay said:
Yes, NYOS reads 8, Red Sea reads 8. Salt mixes at 8, and tank just prior to WC reads 8. I used to see higher Alk with IO salt, but switched to Red Sea blue bucket about 6 months ago due to a bag of IO mixing at 14DKH.

I still think something is off with your tank not using alk but it's hard to believe 2 tests would be off.

In my tank I will always see ALK drop first. And I don't have any sps colonies just frags right now. I'm interested to see what others have to say.

Downbeach · Nov 11, 2015

Are you using RO/DI water for your WC's and top off? The normal uptake of alk and Ca is a ratio of ~ 5 parts alk to every 2 parts Ca, or 50ppm(2.8dKH)Alk to every 20ppm Ca. Considering that there is less alk in reserve in your system, you should see a faster decline in your alk. This includes abiotic precipitation, btw. So, unless there's another source of alk, i.e. tap water, etc. I can't see where the alk would be coming from. Are you using any type of pH buffer? If so, that's where it's likely coming from.

Randy Holmes-Farley · Nov 11, 2015

So just to be clear, you are not adding the alk part of the two part, Triggerjay? And no buffers or other additives except calcium and magnesium?

I agree the top off water question is important. You may also be bringing in copper with it.

Do you have fish and are you feeding them? Have you measured nitrate and phosphate?

Do you have a skimmer?

Triggerjay · Nov 11, 2015

I dose vinegar, mag, and part b of the two part only via dosing pump. All water is RO/DI from a 4 month old 7 stage unit (previous to that was RO only from a RO buddy unit). I have two clowns and a yellow Choris wrasse which I feed flake daily and frozen mysis one cube twice a week. I feed reef-roids and coral frenzy once a week at night with pumps off. I run a bubble magus curve 5 skimmer and skim pretty wet, and for flow I use a quiet one 7000 return from the sump, a maxspect gyre 130 and a pair of jeabo wp25's, one in tank and the other is in the sump to prevent settling of detritus. Phosphate tests unmeasurable using NYOS phosphate kit, and nitrates 5. Tank has been up since February. Glass stays clean requiring cleaning only once monthly. I had an issue with bryopsis and HA prior to the new RO unit, but it has receded to almost nothing as of today. I used to dose kalkwasser, but haven't in months due to high Alk. I do not understand why my Alk doesn't drop. In the past Alk raised with kalkwasser and IO salt but has never dropped on its own. When I got the 14DKH io, I had to do water changes to bring it down with the Red Sea salt.

Triggerjay · Nov 11, 2015

Our municipal water is from an RO plant and they add back some waste. Tap TDS runs 420 and I read 0 out of the RO/DI. My RO unit has three stages of DI and I have noticed that the first DI stage is starting to change color, but second and third DI beads still look new.

Randy Holmes-Farley · Nov 12, 2015

Are you 100% sure you did not mix up the alk product with either the calcium or magnesium?

If you only clean the glass once a month, that suggests that nutrients are VERY low and you may be starving the corals. You might try a product like amino acids or more fish feeding.

Triggerjay · Nov 12, 2015

No, the Alk portion is unopened.

Triggerjay · Nov 12, 2015

I have been thinking about the prodibio amino acid additives. Could possibly be over skimming as its a pretty small system for the curve 5 skimmer. I also run a fairly short photo period. Blues come on at 11am, whites at 1pm. Whites off at 5pm, blues off at 7pm. I checked Alk yesterday afternoon and it tested at 7... One full DKh lower than last week... Thinking its time to start dosing Alk. 8 was a little low to begin with, but I was not concerned as it held there constant for several months. Maybe it was dipping just low enough to make the corals a little unhappy, but not enough to see the result on my test kits, as they only go in 1Dkh increments. I'm thinking if I let it go two weeks without a water change I would see a measurable drop.

So I have two options here. I would prefer my Alk to be a little higher. I would feel comfortable in the 9 range. I have on hand my Alk part of two part, and kalkwasser. My PH runs around 7.8, so based on this I am thinking of going with kalkwasser in the topoff (2 tsp/gal) instead of dosing part two. The kalkwasser would give me the added benefit of raising ph.

Triggerjay · Nov 12, 2015

roadrashpaul · Nov 12, 2015

What is your salinity? How wet are you skimming? Are you skimming very wet and then replacing with ro/di then it could be dropping your salinity over the course between changes.

Triggerjay · Nov 12, 2015

Yes, pretty wet skim. It's wet or nothing with this skimmer. If I try to dry it up, the skimmate collects in the neck and nothing goes in the cup. I check salinity pretty often with a refractometer. Salinity runs at 1.025.

Triggerjay · Nov 12, 2015

This is one day:

roadrashpaul · Nov 12, 2015

Ok just thinking outloud. Doesn't seem to be your issue.

Triggerjay · Nov 12, 2015

I'm thinking at this point my best option is to hold off on today's scheduled water change and measure, measure, measure, and then decide on a course of action. I think my weekly 90% water change is affecting my ability to see what is really going on. I'm "repairing" the issue before it becomes an issue. Red Sea is currently loving my salt mix consumption.