Why do a lot of reefers keep a lower alk in their tank (8-9)?

[ScottB]

Question for the more experienced reefers:

I dose and am keeping my levels where my IO RC salt got my tank to after religious water changes:
Alk: 9.9
Cal: 490
Mag: 1425
Sg: 1.026

However, my nutrients for Nitrate and Phosphate continuously come back as undetectable on my Salifert tests.

Ive tried feeding more and no water changes (was doing a 20g change once every other week on a 65g tank) but am seeing no nutrient readings.

Am I good or bad for a mixed reef?

Your listed parameters are fine, but I would not go higher on ALK until you show/know nutrients. There are caveats to that:
a) Is there any algae growing in your tank? If so, you have nutrient NO3 and PO4 available. It is being taken up by the algae, but is available to your corals.
b) IMO, only the Hanna ULR Phosphate checker has the resolution to measure PO4 at low levels. It is a tool worth owning because while .03 is fine, 0 is bad. (subject to my first point about algae.)
c) Most nitrate tests again offer little resolution on the low side. I've settled on using Red Sea.

 

[X-37B]

I just chose a number.... everywhere said 7-11 is a key alkalinity number so I picked 9. Happy middle, brs also did an investigate about higher levels provided better growth so I will stick to the 9dkh and just maintain it as best as I can do. No science behind my method just decided on a number and stuck to it. All my sps are encrusting or growing

I like this method. Whatever number you chose "stability is #1".

 

[Barnabie Mejia]

To put it simply the GFO and Carbon(mainly GFO) tend to soak some up while doing its main job(phosphate) thus allowing your corals more free alk not trapped by phosphates, leaving you with less alk overall since the corals are also able to use more of it do to less phosphates.

the more scientific explanation.
"Many aquarists using GFO have reported unusually extensive precipitation of carbonates on the solid GFO, and elsewhere in the system. Such precipitation can, for example, be a contributing factor in the caking of such materials, and can coat other surfaces in the aquarium. This precipitation can also contribute to a drop in alkalinity and possibly pH as it removes carbonate from the water column. The effect of calcium will be similar, but smaller on a percentage basis, with a drop of only 20 ppm calcium for every 1 meq/L (2.8 dkH) drop in alkalinity. Increased calcification by corals and coralline algae (possibly spurred by reduced phosphate) can also cause similar drops in calcium, alkalinity, and pH. "

http://www.reefkeeping.com/issues/2004-11/rhf/index.php

Ahhhhh! This makes so much sense! I did notice some white areas in my GFO chamber in my reactor and it wasn't tumbling as it should. I was getting precipitation in there and I didn't even know it! I even sent an email to @BRS thinking that I got a bad batch of GFO (they never got back to me though)…. thanks for the information! even though I'm new to this game, I love learning the little things that can turn into big things. I think the only other place that I have seen the precipitation is on the sand bed, but it is only in a few spots.
my dKH has been consistent at 10.5 for about a month and a half and Calc & Mag have been stable as well. Don't have build up on the powerheads or heater either. I will be doing some more investigating on this!

 

[Phyber]

Your listed parameters are fine, but I would not go higher on ALK until you show/know nutrients. There are caveats to that:
a) Is there any algae growing in your tank? If so, you have nutrient NO3 and PO4 available. It is being taken up by the algae, but is available to your corals.
b) IMO, only the Hanna ULR Phosphate checker has the resolution to measure PO4 at low levels. It is a tool worth owning because while .03 is fine, 0 is bad. (subject to my first point about algae.)
c) Most nitrate tests again offer little resolution on the low side. I've settled on using Red Sea.

I appreciate it!

For algae, I scrape the glass about every day from the fine greenish covering it gets. There's a slight fuzz on some of the rockwork but only until my CUC gets to it. Coraline growing well but I know that's not the same.

I change out filter socks about every 3 days or else they overflow. I also clean my skimmer cup/neck at the same time and it's maybe 20% full of some nasty smelly thick stuff.

 

[Javamahn]

Natural Sea Water is below 8 and i keep low nutrients so I am around 7.7 with far less chance of losing corals as a result of a possible alkalinity spike pushing them over the edge. I don't know what the edge is but I am not willing to find out. I have also read that coloration is better at lower alkalinity but have no expreience yet to that as i am still coloring my little nubs.

 

[BeejReef]

I stick in the upper 8's and back off in the low 9's.
Am blending IO an IORC to mitigate the crazy high alk in the salt mix.
On wc day, I just turn off dosing and haven't yet seen more than a .3dhk swing.

Frankly, I had been targeting 10dkh (influenced by youtube/brs), but things get unstable with too much testing and adjustment. It happily holds 8.8dkh, so I happily leave it there.

 

[tgionet]

I keep it at whatever Red Sea blue bucket mixes at. Alk stays at 8. I always recommend people just run the alk that their chosen salt mix has.

 

[FragileReefer]

Everyone is getting really sciencey with their answers! i keep mine at 8.5 because when i mess up and forget a dose or forget a w/c and it drops to 7.5 i wont lose anything big. i was keeping it at 7.5 and it dropped to 6.8 and i lost a nice blasto. So 8.5 is safe and easy to keep. I have a nano and im dosing All-For-Reef from Tropic Marin.

 

[lapin]

I mix the red sea blue and pro buckets 50/50. My tank likes alk around 9. I listen to my tank and its say stick with 9 and all will be good

 

[Buffalou]

I have been doing this for some time now, had large tanks , small tanks, canister filters, sumps, refug, small skimmers, large skimmers, 2 part, 3part, etc.. everything you can think of, it's all a part of a growing process. You will get some of the best advice you could receive here. It can be overwhelming at times if you let it. For my 2 cents worth, whatever your alk is low, high, or in between, for God's sake and your tank , take it slow. I believe the most difficulties I've had to face was chasing numbers because someone's tank looked great. I failed to realize that most of the great looking tanks were gradual builds , take a lot of time to mature, and have evolved slow and easy. The greatest success I've experienced has been when I made sure the parameters were stable and steady.

 

[Bastray]

I keep my alk at whatever level my salt mixes at. Currently using Brightwell which mixes at 8 so my alk level is 8. I just find it easier to maintain. I’ve thought about switching to Tropic Marin, don’t like the brown crud I get from Brightwell, and if I do I will slowly lower my alk to 7 to match the levels it mixes at.

 

[HigherStandards]

I mix the red sea blue and pro buckets 50/50. My tank likes alk around 9. I listen to my tank and its say stick with 9 and all will be good

I also mix the 2 buckets! Glad to know what I experience is the same as yours.

I keep my DT at 8 its T5 lit with lower nutrients and my Frag tank at 8.5 higher nutrients and light (LED)

 

[CJO]

Pet Peeve / rant here, but we need to stop endorsing newbies adopt 2 part dosing from the start. Joe Smith who starts a 90gallon tank and throws half a dozen 1" SPS frags in it doesn't need a two part. Alk consumption in young tanks is never 'balanced' as alk will get consumed at a much higher rate than calcium, and in bigger tanks the sheer volume of calcium is enough that minimal water changes should replace it faster than a stupid bottle of diluted sidewalk de-icer.

I'm interested in your source about the unbalanced consumption in young tanks. All of the research that I've seen shows that most, if not all, of the inhabitants of the aquarium use calcium and alkalinity in balanced proportions.

I think that having a 2-part system in a new aquarium depends on the person. If they are already overwhelmed, adding another component isn't a good idea.

On the other hand, even though regular water changes should compensate for alkalinity loss in a new aquarium, I also think it's a good idea that new aquariasts learn to test on a regular basis from the beginning, which is mandatory if using a 2-part system. Then it's already setup and they know how to use it once their aquarium needs it. It's better to figure it out when you only have a few small frags than when you have mini colonies.

 

[EMeyer]

Natural Sea Water is below 8 and i keep low nutrients so I am around 7.7 with far less chance of losing corals as a result of a possible alkalinity spike pushing them over the edge.

This. Many people have talked about choosing their alk level based on a "buffer" or a "cushion" -- but my experience matches what you describe. I havent seen low alk hurt corals.

If it dips low, I can slowly bump it back up, and I don't see any mortality. When alk accidentally gets too high, I see widespread death.

So the only cushion I'm worried about is the upper cushion. I'm happier at 7 than 7.5 because its a bigger cushion before it enters dangerous high alk levels.

Alk is one of those things that blow my mind how different peoples tanks are. I know people like the "balanced alk and nutrients" theory, but it doesnt seem to hold up when confronted with actual numbers. (i.e. there are plenty of low nutrient high alk tanks, but anytime I see alk go above 8 I see dead corals). There is something here we still don't understand.

 

[James Franks]

I keep mine aroud 7.7 since that's what my salt mixes at.

 

[Drew in Texas]

I have a well established, long term 150g tank. Prior to that, I had a 1700g tank. The big one stayed in place when I moved. I'm a chemical engineer. I well understand my tenancy to over-analyze most everything. Just how I roll. With my tanks, on the other hand, I use an approach which quite honestly rubs my fur the wrong way but seems to work exceptionally well for *my* tanks. Please, you do what you believe is right for your tanks. I'm not the boss of you.

I see answers from a lot of folks on here that run the gamut on this particular subject. There's a lot of really smart folks who use chemistry to find their solution. Others, through years of experience, have developed systems and theories that they believe are truly the answer. Understand I'm only talking about larger tanks; I have little experience with smaller tank environments. In my 39g QT biocube, I do my water changes with water change out from my large tank.

While I'm cycling my tanks, I make sure I use excellent quality stock (sand, live rock, when it's time, dip my corals before putting them in the DT, fish 100% of the time go thru QT). As is the mantra here, salt tanks take time. As hard as it is, I wait 6-8 months before I put any fish in my tank. So far, this makes perfect sense to me. What follows is what drives me crazy, but I have to let it be because it works for MY tanks.

The purpose of fallowing a tank is to allow the bio-chemical system to stabilize. As I introduce corals, nems and my other inverts (including a sustainable cleanup crew which include snails, conchs, emeralds, sand sifting stars x 2 and hermits), I continually measure all the stuff we religiously test for. Pretty quickly, my tanks settle into their 'numbers' - the numbers which that individual tank will solidly maintain. Attempts to alter the set chemistry are mostly unsuccessful, and forced alteration most often results in disaster.

The parameters my 150 has set into are ever so slightly off what I often see both here and on the interweb as being 'optimal'. My salinity is slightly low, as is my ph, ammonia stays at 0, and I have very slight variation in PO and PO4 levels (but not much). When I change water, it's 30 gallons using Red Sea Coral premium salt mixed to 1.025. *Always*, within a week, it's back to my tanks normal of 1.020.

Understand that everything in me wants to force ALL of the chemistry of my tanks to accepted 'norms', but I have learned over many years of doing this silly, addicting, expensive hobby that I'm not dealing with an experiment that I can manipulate and force to my will. It's a biosystem, and as such will pretty much do what it wants. We can control things like parasites, ammonia high because of death - things outside the norm. But all things being 'normal', we just need to learn to accept that living things don't fit well into rigid boxes and parameters. We have to allow biology the wiggle room it needs to thrive.

My fish, inverts and corals thrive despite their environment not being 'optimal' according to the experts. Drives me CRAZY!

 

[Deaf clown]

I keep mine at 10.5-11 because I use RC and I don’t want to do more work than I need too. I also feed more to keep the corals colored up.

 

[stanleo]

Mine is at 9 dKH (Red Sea test kit)and nitrate is 2ppm and Phosphate is .03 (Salifert for both). I have 1 sps, 1lps, and several softies and they all seem to do well though I don't think I have had the hard corals long enough to determine growth. Not sure how long that is. But GSP and xenia grow like weeds. All the corals color seems to be bright.

 

[Magellan]

I'm interested in your source about the unbalanced consumption in young tanks. All of the research that I've seen shows that most, if not all, of the inhabitants of the aquarium use calcium and alkalinity in balanced proportions.

I think that having a 2-part system in a new aquarium depends on the person. If they are already overwhelmed, adding another component isn't a good idea.

On the other hand, even though regular water changes should compensate for alkalinity loss in a new aquarium, I also think it's a good idea that new aquariasts learn to test on a regular basis from the beginning, which is mandatory if using a 2-part system. Then it's already setup and they know how to use it once their aquarium needs it. It's better to figure it out when you only have a few small frags than when you have mini colonies.

having been one of those new people not so terribly long ago, I can say that the idea of constantly and continuously testing my water in order to dial in 2 part/calcium dosing scared the hell out of me. I still don’t dose calcium or magnesium, (water changes work great too!) and don’t plan too. I am a proponent of the KISS method: Keep It Simple, Stupid! I change the same amount of water over every 10 day period (2x 2.5 gallon water changes in a 28g tank) and lightly dose Alk to keep it slightly higher than 8 that the salt is mixing at. I might not be getting the best growth possible, but I also feel like there are less things that can go wrong (no coral loss so far in almost a year!)

 

[ReefHomieJon]

As I explained earlier, nutrients must be in balance with alkalinity to keep up with the pace of skeleton and tissue growth.

Lower alk. is only better for low nutrient tanks. Nutrients correlate to tissue growth while alkalinity correlates to skeleton growth. In low nutrient tanks, high alkalinity will cause the skeleton to grow faster than the tissue, resulting in burnt tips in mainly acros. With low alk., you won't get the growth, but you will have amazing colors. This is more catered to fully matured reef packed with colonies.

In higher nutrient tanks, lower alkalinity would create disgusting color (subjective to point of view however) with poor growth. With higher alkalinity along with higher nutrients, both can keep up with each other's pace resulting in much faster tissue and skeleton growth, however, due to higher nutrients, you won't get those amazing colors. More catered to frags that you just want to grow out fast as possible.

I have mine at the happy medium however, I still get fast growth and amazing colors.

What do you consider the happy medium?