Alkalinity chemistry question

[Eggpaul]

I check my kh the other day and it was 5. I don't know how long it took to get there. After some tests it seems the tank loses .5 each day. My question is, could there be a point where the kh won't drop anymore? If it drops to 5 and you left it alone, would it be possible to drop to 2 or 1? I'm thinking the sand and rocks maybe won't let it drop further than that.

 

[Animal-Chin]

well it depends on whats going on here, is your coral taking it out of the water, is that why its dropping? Your alk is the measure of carbonate in your water. Carbonate mixes with calcium to form coral skeletons. If your tank sucks it dry your corals cant grow and may die. Something needs to replace it, either water changes or dosing.

 

[mr_X]

Is this a coral tank? The lower the alkalinity, the more acidic the water.
You'll never be able to keep corals with alkalinity that low. I don't know the answer to your question though..I'm sure the calcium based rock and substrate may buffer somewhat.
Why not just add whatever amount of soda ash you need to keep it at say....8?

 

[Eggpaul]

Is this a coral tank? The lower the alkalinity, the more acidic the water.
You'll never be able to keep corals with alkalinity that low. I don't know the answer to your question though..I'm sure the calcium based rock and substrate may buffer somewhat.
Why not just add whatever amount of soda ash you need to keep it at say....8?

Yes, I'm taking the steps to correct it by getting dosing pumps. Some Corals started acting up a few months ago, might be the same time kh dropped

 

[Sniperhank]

My alk is always low. I usually use some of my soft coral to 'track' it if I need to dose it back up. I want to say with sand and rock it shouldn't be able to go lower than 6-7...are you sure it was 5? I never thought it could go that low.

 

[Animal-Chin]

I've seen a 5 when I first got into SPS. It can happen...

 

[Eggpaul]

My alk is always low. I usually use some of my soft coral to 'track' it if I need to dose it back up. I want to say with sand and rock it shouldn't be able to go lower than 6-7...are you sure it was 5? I never thought it could go that low.

Yes, it was 5. Pretty heavily stocked with lps. No wonder some started dying. After two years I'm learning knew things. Sad I lost a few great corals. One frogspawn that split into 8 heads isn't doing well.

 

[mr_X]

Just manually add alk buffer in the morning, and at night when you get home from work until you get the dosing pump. BRS sells bulk additives pretty cheap.

 

[Sniperhank]

The BRS kit for dosing is pretty nice period. Though just the additive, a jug, and a pump it sure makes life extremely easy. Don't remember if it came with the measuring cup and funnel or not.

 

[Eggpaul]

The BRS kit for dosing is pretty nice period. Though just the additive, a jug, and a pump it sure makes life extremely easy. Don't remember if it came with the measuring cup and funnel or not.

Trying to see if I should use kalkwasser instead. I don't have a lot of evaporation. My ph is between 7.95 and 8.03. Is that too low? Kalkwasser scares me. Don't know how much to dose. 2 part seems more stable

 

[Gregcoyote]

Kalkwasser doesn't raise carbonate hardness. It does add a excellent source of calcium. The ph controls how much calcium is dissolved back out of the substrate, if it's aragonite. But that doesn't happen unless ph gets below 7 at which time you have other issues.

A KH of 5 will nuke your LPS, but you know that already. Start adding soda ash or properly prepared baking soda. This can be bought for pennies. Slowly, over a week. I suggest shooting for 9-10Kh. Monitor calcium as that may tend to drop as hardness increases. You need to also check to see that Mg levels are about 1300. All three of these relate to each other. The proper Mg levels decreased the "see saw" effect between calcium and carbonates.

But with a light coral load, you might consider increased water exchanges with a reef salt that's higher in hardness.


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[Sniperhank]

Salt mix plays a part as well, as it will have differing numbers for these elements. Though I really like Kent's salt, the low alk that comes with it seems to keep me in the lower than wanted alk area.

 

[Eggpaul]

Kalkwasser doesn't raise carbonate hardness. It does add a excellent source of calcium. The ph controls how much calcium is dissolved back out of the substrate, if it's aragonite. But that doesn't happen unless ph gets below 7 at which time you have other issues.

A KH of 5 will nuke your LPS, but you know that already. Start adding soda ash or properly prepared baking soda. This can be bought for pennies. Slowly, over a week. I suggest shooting for 9-10Kh. Monitor calcium as that may tend to drop as hardness increases. You need to also check to see that Mg levels are about 1300. All three of these relate to each other. The proper Mg levels decreased the "see saw" effect between calcium and carbonates.

But with a light coral load, you might consider increased water exchanges with a reef salt that's higher in hardness.


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Yes, 5 KH was a disaster to my hammer and frogspawn. Really frustrating. It just got my by surprise. My tank has so much corals, there is hardly any room for any more. Just ordered the dosing kit from BRS. I will try to aim for 450 calcium and 9 kh. Does that sound good or should kh be 10? I just got my MG test kit so let's see where that is at! I use Red Sea coral pro, so of course it has elevated levels. I usually do a water change once a month %25. Guess dosing was the missing element.

 

[Gregcoyote]

I made the same mistake the first time I ran GFO. It can also lower alkalinity.


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[Eggpaul]

Mg is at 1470, just did test.