low alkalinity

[makana]

My PH is 8.1, Cal 440ppm, Sal 34ppt, but Alk is only 7dkh. I have read that low alkalinity can be caused by the initial cycle but can't find out if it will recover now that the cycle is done.

Is low alk part of the cycle? Should I raise it or will it sort itself out?

[Delphinus]

Ok two things, one a sort of general comment and one more a direct answer to your question.

Generally speaking, Alk is not something that will sort itself out. As consumables, Calcium and Alkalinity go hand in hand. A high calcium reading means nothing without the corresponding alkalinity reading. There's a sort of see-saw effect if you don't actively manage both parameters - if alk is low, it's not uncommon to see a high calcium reading and vice-versa. If calcium is the bricks, or building blocks, for growing corals, then alkalinity is the mortar that holds the bricks together. Or alkalinity is the money in your wallet: if you're at Home Depot and they have thousands of bricks, without money to buy the bricks, all you can do is look at them sadly and wish you could buy them.

Ok, so reef tank lesson aside, the specific answer to your question is low alk is not part of your cycle. However, as things start to grow in your tank, you will notice a draw on your alk and Ca until the point they get out of balance and then things can't pull any more Ca out of your water. So you compensate by dosing, or water changes, or reactors, or whatever your favourite way of doing it, and then you see corals and stuff grow again.

But .. having said all that ... 7dKH is in fact a natural seawater kind of reading for alk. If you look at the zeovit prescriptions for example, they recommend targetting your Alk at 7dKH since they believe there is no benefit to an elevated alk beyond NSW levels. However some people like higher Alk anyhow because it contributes to increased growth rates of stoney corals (although even softeys benefit from "good" Ca/Alk numbers - they maybe just use less of it, so you add less, but it's still important to target "good" numbers).

So: 1) It won't sort itself out, you'll need to track this number and deal with it as it fluctuates 2) It's not really part of the cycle but it will start to deplete over time, and 3) 7dKH is not really a low alkalinity reading, no need to panic as yet, it's a good number to maintain Alk at for now.

Hope this helps.

[makana]

I was aware that calcium and alk go hand in hand. From what I have read my calcium seems in the normal range but I read many posts that said in an aquarium alk should never go lower than 8 so I was a little concerned.

I also read that low alk is caused by CO2 wich can be caused by poor water flow and the tank cycle so thats why I thought it might sort itself out.

But seeing as how there is nothing in my tank other than live rock, algea, and snails, what would be bringing down my alk? Or is this just the level of alk that my salt mix produces?

Should I be concerned down the road? If my alk is at the bottom of the scale with no coral will I be having problems when it comes time to add them?

Thanks for the help!

[whatcaneyedo]

Here is a link that will teach you everything you need to know about alkalinity. In the referances at the bottom of the page there is more information to give you an even better understanding.

CHEMISTRY AND THE AQUARIUM by RANDY HOLMES-FARLEY
Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

I find this to be extremely helpful for adjusting my alkalinity as well as calcium and magnesium.

Reef Chemistry Calculator
http://reef.diesyst.com/chemcalc/chemcalc.html

[Delphinus]

Sorry, I realize you probably knew that bit about Ca and Alk being coupled but I just sort of had to include those comments so that the rest of what I was saying would make sense. In general I would say that 8 is indeed better than 7 but I don't think 7 is too low in and of itself. I wouldn't want it any lower, so it's better to shoot for 8 if you're going to to track it.

Most likely this is indeed where your salt is mixing. There may be a slight draw already but its not huge.

I wouldn't say you need to be "concerned" down the road but ultimately keeping track of Ca and Alk is something you do want to put a little attention on. Finding your own comfort zone is key. For me what works is 2-part dosing (I dose Ca in the morning, Alk at night) and then testing once per week to see if I'm adding back at roughly the same rate they are being used up. As corals grow (and clams, and so on), or as you add corals, the rate Ca and Alk are consumed goes up, and thus you have to add more as time goes on. But you don't have to follow this example. Some people just dose weekly. Some people don't dose at all, but my advice is that Ca and Alk are things you do want to dose and test for on a regular basis since relying on your salt mix to make up for it isn't really the best practice - it just can't follow the dynamics of consumption and growth as well as you can.

[makana]

Thanks for all the help! I think I might try and raise it a bit. I'd rather learn how to control the chemistry now rather than after I add livestock.

[don.ald]

[quote=Delphinus;370882]Sorry, I realize you probably knew that bit about Ca and Alk being coupled but I just sort of had to include those comments so that the rest of what I was saying would make sense. In general I would say that 8 is indeed better than 7 but I don't think 7 is too low in and of itself. I wouldn't want it any lower, so it's better to shoot for 8 if you're going to to track it.

Most likely this is indeed where your salt is mixing. There may be a slight draw already but its not huge.

I wouldn't say you need to be "concerned" down the road but ultimately keeping track of Ca and Alk is something you do want to put a little attention on. Finding your own comfort zone is key. For me what works is 2-part dosing (I dose Ca in the morning, Alk at night) and then testing once per week to see if I'm adding back at roughly the same rate they are being used up. As corals grow (and clams, and so on), or as you add corals, the rate Ca and Alk are consumed goes up, and thus you have to add more as time goes on. But you don't have to follow this example. Some people just dose weekly. Some people don't dose at all, but my advice is that Ca and Alk are things you do want to dose and test for on a regular basis since relying on your salt mix to make up for it isn't really the best practice - it just can't follow the dynamics of consumption and growth as well as you can. [/QUOTE

can you explain your dosing process? i.e. manual or mechanically?
thanks

[reefermadness]

I think getting used to adjusting and dosing your chemistry now is a good idea. Also you want balanced calcium and alkalinity. I think 420ppm is balanced with 8dkh....I think those would be good numbers to strive for IME.

[Delphinus]

Originally Posted by don.ald

can you explain your dosing process? i.e. manual or mechanically?
thanks

I don't do anything automated as yet but was thinking of ordering some peristaltic pumps in the new year to automate the process. Having said that, Aqualifter pumps (sort of like an air pump but for water) are dirt cheap ($10) and probably would do the trick just fine.

I use Seachem "Reef Advantage" for Ca and "Reef Builder" for Alk. The instructions call for dissolving in tank water first, I don't even bother. I have some measuring spoons from a kitchen store (eg. 2.5ml, 5ml, 15ml, etc.) that I use to measure out what I need and I dump it in a high flow area of my sump. The important thing with dosing 2-parters is that you don't add them at the same time (they react with each other) so I do one in the morning before I leave for work and another in the evening after I'm done feeding the fish and so on.

You can use other 2-parter brands though, or you can even order the stuff in bulk. You can make your own alk additive using baking soda and washing soda too if you're inclined. No real hard and fast rules here.

[don.ald]

tanks for the dosing info...where do you pick-up the $10 pumps?