Alkalinity dropping but calcium sky high?

[Ocelaris]

So I've gotten myself in a bind. My calcium was low for a while and I managed to get it up, but it kept going up till its at 500. But that's not the problem. I've cut calcium way back, like 65mL a day, but alkalinity has plummeted from 9.5 to 8.2 in 10 days. I'm at 95mL a day calcium carbonate and in the past two days I've added 10mL more per day (2x5mL increase two days apart). No visible signs of precipitation. It's about 250 gallons, 18 month old tank.

1) should I stop dosing so unequally and pause a day and get them equal?

2) Should I continue treating alkalinity as a separate beast and manage that as needed?

I attribute my problems to my cheap brs dosers and homemade dosing containers for the unequal dosing. If the levels get too low in the containers it seems to suck more air. Really need to get a more reliable dosing system. Also phosphates have just gotten under control (. 06) and brand new t5 bulbs (10x80w) might be responsible for more alkalinity uptake. Otherwise everything looks great, I'm just worried I'm on the edge of unstable dosing with it being so uneven.

Thanks!

 

[SPR1968]

Just dose each in amounts required as there taken up by the system. All your doing is trying to keep them stable and balanced to were you want the levels

If the dosers aren't working properly your always going to be fighting problems so maybe sort those out as needed.

 

[hyprc]

Always, always, always dose equal amounts alk and calcium. Make sure Mag is above 1250 at all times. Break either of those rules and you're asking for an imbalance in my experience. If you have a big imbalance, water changes are your only reasonable solution IMO. Also, I only dose by hand because I don't trust dosers (and good ones are expensive!).

 

[Randy Holmes-Farley Verified Community Expert]

If you have a big imbalance, water changes are your only reasonable solution IMO. Also, I only dose by hand because I don't trust dosers (and good ones are expensive!).

It works well to correct true calcium and alkalinity imbalances just by selectively dosing what you need and not what you do not need. Water changes are an expensive way to make corrections.

 

[Ocelaris]

Thanks, I'll stay the course and just keep an eye on it. I do a 30 gallon brute water change every week, just because it's what my corals like.

It's almost a religion, dosing, we have all these rules and try to stay true to them, but when things go bad we come to confess at the altar of Randy and seek solace!

Definitely looking at new dosers, but the problem is you really never know if it's the equipment or changes to the tank chemistry or biology. Could I get better dosers, yes, but testing is the only way to be sure! Someday I'll get an alkatronic or Triton.

Thanks!

 

[hyprc]

It works well to correct true calcium and alkalinity imbalances just by selectively dosing what you need and not what you do not need. Water changes are an expensive way to make corrections.

I'd usually agree, but isn't that how he got into this situation?

 

[blasterman]

IMO, you dose and dial in to keep alk as stable as possible as your first priority and worry about calcium second. If you can get both stable with automated dosing...great. However, given a choice between keeping one stable and having to manually correct the other you *ALWAYS* get alk stable first. Er on the underside with calcium because it's easy to raise it manually or correct with a water change. You then tweak calcium gradually to get it in line because it's going to be consumed slower anyways.

 

[Ocelaris]

I probably got into this situation because I didn't test frequently enough and my dosers were uneven (my hypothesis). If I still see alkalinity drop still while increasing it, I'll assume precipitation is happening. I think where people get off track is the precipitation that they don't see. I'm not dosing that much where I think it's occurring based on my water volume and number of sps. But I'll find out in a few days if I can't get alk up by increasing the dose slowly, I'll stop for a day and measure my usage.

 

[Randy Holmes-Farley Verified Community Expert]

I'd usually agree, but isn't that how he got into this situation?

Only if he did it incorrectly. Correct dosing never leads to imbalances.

 

[Ocelaris]

I'm really curious how much alkalinity consumption varies based on biological needs vs. Dosing problems (or mixing mistakes). I may start a thread asking the alkatronic and Triton users if they see a wide range of consumption. Until then it's a guess if it's our equipment, procedures or biology.

 

[Randy Holmes-Farley Verified Community Expert]

I'm really curious how much alkalinity consumption varies based on biological needs vs. Dosing problems (or mixing mistakes). I may start a thread asking the alkatronic and Triton users if they see a wide range of consumption. Until then it's a guess if it's our equipment, procedures or biology.

I think we have a very good understanding of the alkalinity consumption in reef tanks. It does vary with tank inhabitants, pH, and the absolute alkalinity value, but its typically 0.5-4 dKH per day.

The question that is out there, IMO, is how much of that is actual organism use and how much is abiotic prteciptiation in any given aquarium.

A secondary question is what time of day it is used (mostly during the day) and why that is (could be the higher pH driving either organisms consumption or abiotic precipitation) or the light cycle coupling directly to photosynthesis.

 

[Ocelaris]

It's funny, 20 years ago I did a science experiment for school with Eric Borneman's help, trying to replicate Craig Bingmans experiment asking a similar question about calcium carbonate uptake and I'm still here asking the same question

I reread Randy's article on precipitation (http://reefkeeping.com/issues/2005-07/rhf/index.php) and I think my problem is also partially due to my aggressive use of gfo. I've been trying to get phosphates down and the alkalinity falling corresponds well with my switching to new gfo last weekend.

I'm at 7.9dkh and after a 30 gallon water change with reef crystals I'm still at 7.9. I've cut off all dosing and will start back up, maybe with sodium bicarbonate as I have just a little left. I'll check phosphates later and if I'm very low I'll take the gfo offline. Thanks again for all the help.