Help me figure out what to do about my alkalinity

[JayFish4004]

I’ve been at this for about a year and a half and how to handle alkalinity on my specific tank is still a bit of a mystery for me.

My salt mixes at 9.8dkh - so 2 weeks ago I brought my alkalinity up to 9dkh from 8dkh using sodium bicarbonate thinking I could stabilize at 9 with my weekly 20% change.

I don’t have a lot of corals consuming alk in my 20 gallon - my consumption is very low, which is why I am very confused that its already back to 8dkh today.

My biggest question - if my tank wants to sit at 8dkh do I just let it? Im not sure if the effort is worth it to keep it at 9dkh if the tank wants to pull it back down. Im not quite mentally prepared for an alk doser just yet, and curious how 20% weekly changes doesnt get me where I need to be.

 

[Reefer Matt]

I’ve been at this for about a year and a half and how to handle alkalinity on my specific tank is still a bit of a mystery for me.

My salt mixes at 9.8dkh - so 2 weeks ago I brought my alkalinity up to 9dkh from 8dkh using sodium bicarbonate thinking I could stabilize at 9 with my weekly 20% change.

I don’t have a lot of corals consuming alk in my 20 gallon - my consumption is very low, which is why I am very confused that its already back to 8dkh today.

My biggest question - if my tank wants to sit at 8dkh do I just let it? Im not sure if the effort is worth it to keep it at 9dkh if the tank wants to pull it back down. Im not quite mentally prepared for an alk doser just yet, and curious how 20% weekly changes doesnt get me where I need to be.

What test kit are you using?

 

[JayFish4004]

What test kit are you using?

I use the Hanna test kit for Alk.

 

[Jekyl]

Unless a small nano tank, dosing is much more effective and cheaper than water changes. I only actually change water when my nitrate gets too high, which is 2 or 3 times a year. Measure alkalinity 2 or 3 times a week for the next couple weeks. Document the consumption, then dose daily to keep stable. Test as you go to determine if dosage needs tweaking.

 

[JayFish4004]

Unless a small bank tank, dosing is much more effective and cheaper than water changes. I only actually change water when my nitrate gets too high, which is 2 or 3 times a year. Measure alkalinity 2 or 3 times a week for the next couple weeks. Document the consumption, then dose daily to keep stable. Test as you go to determine if dosage needs tweaking.

If my tank is stable at 8 without dosing would you still suggest dosing to keep it stable at 9? My goal is for stuff to be happy and healthy - in a 20 gallon growth is less important for me, and Id much prefer to be as hands off as possible given I already do a heavy WC schedule.

Unfortunately I have 9 fish so not changing water would get ugly quick for me in my 20 gallon.

 

[Jekyl]

If my tank is stable at 8 without dosing would you still suggest dosing to keep it stable at 9? My goal is for stuff to be happy and healthy - in a 20 gallon growth is less important for me, and Id much prefer to be as hands off as possible given I already do a heavy WC schedule.

Unfortunately I have 9 fish so not changing water would get ugly quick for me in my 20 gallon.

With an overstocked tank like that you'll have to base the numbers off what the salt gives. Should try not to have more than a 1dkh swing in a day though.

 

[vetteguy53081]

I’ve been at this for about a year and a half and how to handle alkalinity on my specific tank is still a bit of a mystery for me.

My salt mixes at 9.8dkh - so 2 weeks ago I brought my alkalinity up to 9dkh from 8dkh using sodium bicarbonate thinking I could stabilize at 9 with my weekly 20% change.

I don’t have a lot of corals consuming alk in my 20 gallon - my consumption is very low, which is why I am very confused that its already back to 8dkh today.

My biggest question - if my tank wants to sit at 8dkh do I just let it? Im not sure if the effort is worth it to keep it at 9dkh if the tank wants to pull it back down. Im not quite mentally prepared for an alk doser just yet, and curious how 20% weekly changes doesnt get me where I need to be.

8dkh is acceptable, even 7.7 as the range is 8-11dkh - Safe range I should say and seawater is generally about 8.
Do realize Alk is affected by calcium in which there's a close link between high alkalinity and a reduction in calcium. Higher cA levels can reduce the amount of alk, so a balance has to be established.

 

[mdb_talon]

I’ve been at this for about a year and a half and how to handle alkalinity on my specific tank is still a bit of a mystery for me.

My salt mixes at 9.8dkh - so 2 weeks ago I brought my alkalinity up to 9dkh from 8dkh using sodium bicarbonate thinking I could stabilize at 9 with my weekly 20% change.

I don’t have a lot of corals consuming alk in my 20 gallon - my consumption is very low, which is why I am very confused that its already back to 8dkh today.

My biggest question - if my tank wants to sit at 8dkh do I just let it? Im not sure if the effort is worth it to keep it at 9dkh if the tank wants to pull it back down. Im not quite mentally prepared for an alk doser just yet, and curious how 20% weekly changes doesnt get me where I need to be.

For starters I would say that 8dkh is just fine and if you want to keep it there that is no problem at all. As for 20% weekly water changes not keeping you at 9 that is because it is hard to keep your alkalinity from dropping if you run your tank at anywhere near the salt mixture dkh....over time it always going to go down. If on the other hand your makeup salt is significantly higher than the level in the tank then in a low consumption tank it can work just fine. I believe this is what you are experiencing in why it's hard to keep at 9 but water changes can keep it at 8.

 

[JayFish4004]

With an overstocked tank like that you'll have to base the numbers off what the salt gives. Should try not to have more than a 1dkh swing in a day though.

I wouldn’t go as far as to say its overstoked - the 9 fish are all nano (2 barnacle blennies, 2 mandarins, 2 threadfin cardinals, pinkbar goby, neon goby, citron goby).

Mainly just requires more food than most to keep the fish happy and healthy. I use rowaphos now to keep phos under control - nitrates are at 18ppm and phos is 0.03ppm.

 

[JayFish4004]

For starters I would say that 8dkh is just fine and if you want to keep it there that is no problem at all. As for 20% weekly water changes not keeping you at 9 that is because it is hard to keep your alkalinity from dropping if you run your tank at anywhere near the salt mixture dkh....over time it always going to go down. If on the other hand your makeup salt is significantly higher than the level in the tank then in a low consumption tank it can work just fine. I believe this is what you are experiencing in why it's hard to keep at 9 but water changes can keep it at 8.

I would prefer to avoid dosing if at all possible - my LFS says its inevitable that I will need to at some point, but it just seems like a lot of extra work and stuff to think about so I really want the juice to be worth the squeeze to go down that route. If there’s no drastic difference between 8dkh and 9dkh I would prefer to stay the course.

 

[nereefpat]

My biggest question - if my tank wants to sit at 8dkh do I just let it?

Nothing wrong with 8 dKH. That isn't low, actually higher than natural seawater.
If your tank stays at 8 with water changes, you likely don't need to dose...yet.

 

[Fishyfish22]

If my tank is stable at 8 without dosing would you still suggest dosing to keep it stable at 9? My goal is for stuff to be happy and healthy - in a 20 gallon growth is less important for me, and Id much prefer to be as hands off as possible given I already do a heavy WC schedule.

Unfortunately I have 9 fish so not changing water would get ugly quick for me in my 20 gallon.

It all comes down to the biology. Assuming theres no leaks or precipitate forming, Alk goes down because your coral are active and using it to build their skeletons. Check your calcium see if that has changed as well. In a smaller tank dosing might be the best solution, or just throw some baking soda in every now and then and it'll go up. A little goes a long way though so be careful.