How low do you keep your alkalinity and why?

[Scott.h]

Over the last few months I've been lowering my kh on purpose. As my new tank matures my no3/po4 dropped to undetectable and my colors started to fade a bit. I started dosing potassium nitrate to compensate for this, so it's hasn't been an ultra low system for over a month. I've had some residual in my ato water, but haven't added any in about a month.

The deal is this: I have a few newer sps frags that the tips keep burning and healing. I also have some sps that never were effected at all. If I don't dose alk they seem to heal, but obviously I have to. It's to the point where I've been testing (salifert) 2x a day and the number is 7.0. My nitrates are around 5, and id like to see it 2.5, which I feel is manageable now. I've also shut off my dos to manually dose, but I was doing 4 doses a day 6 hours apart. And each dose was done over a ten minute period. So these doses were no shock to the system. No visible swing in ph either.

I feel this burn is related to one of 4 things. My kh is still too high, aluminum leaching from my 6 month old marine pure blocks, something wrong with the two part itself, or caused from adding potassium nitrate. I'm leaning against the last because I've seen recession come and go since I quit adding nitrate, but still possible. I will be sending some water to triton soon, but until I get the results I wondered how many people keep their kh lower then 7, and if for the same reason as what I'm feeling?

 

[Randy Holmes-Farley Verified Community Expert]

With adequate nutrition, high alkalinity doesn't generally lead to any problem.

Have you determined if you might be too low in phosphate?

 

[Scott.h]

With adequate nutrition, high alkalinity doesn't generally lead to any problem.

Have you determined if you might be too low in phosphate?

It's been detectable for a few months. Judging by color .01. The first thing I did was ditch gfo, Carbon, and harvested a majority of the macro algae. Before I started dosing nitrate I was over feeding the (4) fish and adding coral food with little/no rise in no3 and po4. So about a 1.5 months ago I started the nitrate dosing. The last month I've left my hands out of the tank as much as possible. And things started to heal. 1 tbsp coral food every other day in 100 gallons of water. 10 gal a week water change, daily checking, dosing pump... Out of nowhere some of the tips regressed again this week. It looks like an alk burn to me but it doesn't make sense. Everything is in check from what I can test and see. I've considered going to kalk but I don't want to change things drastically either.

 

[Coral Addict]

Keep mine right around 8.5 really want to find a salt that matches where your trying to keep your reef. Makes it easier to maintain

 

[Scott.h]

I'm using tropic Marin pro reef because of that. It's 7-8 freshly mixed. Today I even brought my new salt down to 7.2 so it didn't spike the tank, just in case.

 

[Scott.h]

I don't know if this makes sense, but I kept my alkalinity at 8.0. When my nutrient levels got to zero I got tip burn. So I let it fall naturally down to 7.0, and tried to keep it there. It showed improvement so I started dosing again, small amounts. Dosing less then what it takes to maintain a steady number. While it fell on its own, and 2-3 ml a day things started to heal over 3 weeks. When I dose small amounts it was fine. But kh falls low, obviously. It takes 4 milliliters a day to maintain a rocksolid alkalinity number right now. 100% sure.. Opened a new kit etc, But when I get up to 4 mL of dosing, no matter how I break it up the dosing, I see a negitive impact. So my natural instinct say let the alkalinity drop lower. But I've never kept a tank with lower alkalinity that I have right now, so I don't know that that's the problem. Again, this isn't all SPS, just some. I'm shooting from the hip but I wonder if there something wrong with the two part. I feel like I'm dosing poison.

 

[Scott.h]

@twilliard , can you tell me if you've witnessed any tip burn or recession with nitrate dosing?

 

[greg 45]

I always want to know why bank in early reef keeping people ran there alk at 12 plus.
There was never a issue with burnt tips or any other sps problems back then.
Now that we have ultra low nutrient there is a trend to match sea water .
WHY please advise .

 

[Mal11224]

You will probably find a lot of opinions here. I keep my alk @ 10 dkh. And calcium at 450. I have a mixed tank and I also use Red Sea A B C and D to supplement. I have not had any issues with the high alkalinity on my fish or corals. The growth is good as a result. I also feed a lot and because I have a fuge, I do not see high spikes in nitrates. Alkalinity plays a big role in the photosynthesis process of corals. In essence, the lower the alkalinity, the less effective photosynthesis will be. Don't get me wrong, there is such a thing as too much alkalinity, but with the right amount, you can inhibit good growth in your reef.
In my opinion, if you are going for a low nutrient system, you will need to use some form of supplements regularly and find a suitable alkalinity level for your corals. Find the routine that works and stick with it.

 

[reeferfoxx]

I always want to know why bank in early reef keeping people ran there alk at 12 plus.

You can still do that just depends on how much nutrients you keep. You know, trends come and go and with the interwebs we havea great deal of more information. Also back in the day keeping certain sps and some lps were deemed impossible. And 5 inch sandbeds were the way to go.

Fwiw keeping Alk in the 7-8 range has suited my mixed reef tanks. I skim and have a small fuge. Nutrients usually stay consistent however nitrates fluctuate for me.

I don't know if this makes sense, but I kept my alkalinity at 8.0. When my nutrient levels got to zero I got tip burn. So I let it fall naturally down to 7.0, and tried to keep it there. It showed improvement so I started dosing again, small amounts. Dosing less then what it takes to maintain a steady number. While it fell on its own, and 2-3 ml a day things started to heal over 3 weeks. When I dose small amounts it was fine. But kh falls low, obviously. It takes 4 milliliters a day to maintain a rocksolid alkalinity number right now. 100% sure.. Opened a new kit etc, But when I get up to 4 mL of dosing, no matter how I break it up the dosing, I see a negitive impact. So my natural instinct say let the alkalinity drop lower. But I've never kept a tank with lower alkalinity that I have right now, so I don't know that that's the problem. Again, this isn't all SPS, just some. I'm shooting from the hip but I wonder if there something wrong with the two part. I feel like I'm dosing poison.

Problem I see here is the constant dosing, nutrient fluctuations, possibly inconsistent husbandry(just a guess). Seems you can't decide on what parameters to keep. Often times reefers pick up dosing methods(balling, zeovit, Af) for nutrient control and to gain the edge on color. Problem is getting things just right. Trying skim, fuge, atf, reactors, chemical filtration plus dosing ABC and 123 with bio this and that bla bla. You'll never find a happy medium.

 

[GoVols]

8-9 dkh
Why?... My reef likes it.

 

[reeferfoxx]

It's been detectable for a few months. Judging by color .01.

I missed this here! Not sure about you but doing po4 tests with color identifiers is not a day in the park. I just cant trust it. I do recommend Hanna ULR po4 checker the pbb one. This is a more accurate test and easiest imo. But.. Lets play with this and say your po4 was consistent for a few months at .01. That is a decent number and more towards the lower spectrum. IF it were ME, judging by that number, i would keep MY alk around 7.0 and 7.3. And no higher tha. 7.5. I would then keep those ranges there. Mark calendar of wc or skimmer cleaning etc. Don't fudge on feeding regimens and keep testing no3 and alk and see if you can record those readings and certain times and look for a pattern.

 

[Makomek]

Two weeks ago I dosed nitrate (stomp remover)to raise to 2-3 ppm trying to see if my corals are getting better color. I keep my alk at 7.5-8 and with nitrate dosing my corals went dowhill with lot of red slime. I since stop dosing nitrate and do lot of small wc lately. I think nitrate dosing is not for evryone and most time can cause more harm then good. I notice a year ago when my alk is at 6-6.5 my sps have crazy PE and color. I'm going to let alk drop to 6 on my ULN tank and see how it goes. This my second time trying nitrate dosing and both fail attemp with a lot of headach.

 

[reeferfoxx]

Two weeks ago I dosed nitrate (stomp remover)to raise to 2-3 ppm trying to see if my corals are getting better color. I keep my alk at 7.5-8 and with nitrate dosing my corals went dowhill with lot of red slime. I since stop dosing nitrate and do lot of small wc lately. I think nitrate dosing is not for evryone and most time can cause more harm then good. I notice a year ago when my alk is at 6-6.5 my sps have crazy PE and color. I'm going to let alk drop to 6 on my ULN tank and see how it goes. This my second time trying nitrate dosing and both fail attemp with a lot of headach.

Interesting. Without arguing your statement, i am curious about a couple things. Don't take offense but..
How old is your tank?
What test kit is used to test alk?
What were your initial PO4 readings prior to kno3 dosing?
Any other dosings in addition to kno3 such as carbon dosing?

 

[Makomek]

My current tank been running 16mos. I used salifert for alk/cal/mag/no3 and hanna checker for po4. My system is ULN with very small bioload so undetectable no3/po4 since the beginning. I kalk on a dosing and brs soda ash to keep alk stable, calcium maintained with kalk and WC, no cabon dosing.

 

[Makomek]

With My UNL system I have good PE but the color and growth is just not there. I've seen very nice sps tank with little po4/no3 but I can never get those two to move up, the more I fed the more algae I got and still at zero so that's where nitrate dosing come to mind

 

[reeferfoxx]

My current tank been running 16mos. I used salifert for alk/cal/mag/no3 and hanna checker for po4. My system is ULN with very small bioload so undetectable no3/po4 since the beginning. I kalk on a dosing and brs soda ash to keep alk stable, calcium maintained with kalk and WC, no cabon dosing.

Thank you for that and the additional information! Out of curiosity do you by any chance notice any white dusting on pumps or powerheads that wouldn't otherwise be grey like detritus? I ask because of the use of kalk and how it impacts pH and calcium carbonate. What happens is phosphates can bind to calcium carbonate in the process of calcium phosphate precipitation. Put simply, your available po4 could be locked in the rocks or sandbed or bound to calcium in the form of crystals and easily removed with a protein skimmer(if you have one).
Randy wrote an article about this here. I recommend reading it since you are using kalk.

With My UNL system I have good PE but the color and growth is just not there. I've seen very nice sps tank with little po4/no3 but I can never get those two to move up, the more I fed the more algae I got and still at zero so that's where nitrate dosing come to mind

So the meta behind dosing kno3 or to increase NO3 is to help maintain N and P balance. Typically reefers run into problems and come to find out the have plenty of po4 available in the water column, but no NO3. This type of imbalance would cause algae growth or cyanobacteria. So, in your case assuming Cyano wasn't present prior to dosing (since not much po4 is available in the water column) you've inadvertently created an imbalance for cyano to thrive.

Honestly, I have an idea of how to help if calcium phosphate precip is the culprit. However, I don't want to give any suggestions at this point until we know for sure.

 

[Makomek]

Yes I have white dusting when I first used kalk but after dosing at high flow area I don't have it since. I'm running a skimmer yes it's not helping what I'm trying to achieve here but without it my ph drop to dangerous level due to my co2 in my house. To me alk 6-6.5 is the number I don't like to be at but my sps loves it. Yes I think dosing nitrate throw my po4 out of wack or something idk and my sps turn whiter with some burn tip.

 

[reeferfoxx]

Yes I have white dusting when I first used kalk but after dosing at high flow area I don't have it since. I'm running a skimmer yes it's not helping what I'm trying to achieve here but without it my ph drop to dangerous level due to my co2 in my house. To me alk 6-6.5 is the number I don't like to be at but my sps loves it. Yes I think dosing nitrate throw my po4 out of wack or something idk and my sps turn whiter with some burn tip.

Just keep in mind that with the addition of the skimmer helping increase pH and the kalk(increasing pH) you will still have precipitation with or without high flow in the kalk 'area'. You should be monitoring pH and making sure it's not spiking more than 8.5. Your sps might like the alk at 6.5, your pH was most likely lower thus helping dissolve calcium precip. Lowering pH temporarily to 7.8 can help dissolve the calcium precipitation and release PO4 that might be locked.Though it may work, i'm not sure on the longevity. I would like to recommend you keep Alk at 7dkh(no more, no less) and let the process happen at a slower pace. Your sps will adjust. Just a suggestion, you don't have to. Cheers!

 

[reeferfoxx]

Your sps might like the alk around 6.5 just because at that low of level which is getting close to neutral, is dissolving the calcium precip. and helping release nutrients back into the water column.

Edit: After reading what I wrote here, i realized I was mixing up two different things. Too much sun this weekend. What I ment to say is when alk was at 6.5 your pH was most likely lower thus helping dissolve calcium precip. Lowering pH temporarily to 7.8 can help dissolve the calcium precipitation and release PO4 that might be locked.