Can GFO significantly affect Alkalinity?

[GoPitt88]

My reason for asking is that I recently started paying attention to my Alkalinity. I have a 2 year old 55 gallon mixed reef (15 corals, of which 4 are SPS, 4 are LPS, and the rest are a variety of softies). I tested my Alkalinity a couple weeks ago to find it at 4.0 dKH (yikes!) Everything looks good however. Anyway, I'm in the process of slowly raising it to the 8.0 to 9.0 range using sodium bicarbonate. Have just dosed my ATO water with Kalkwasser (1 teaspoon per gallon to start with) but noticed while slowly raising my dKH, that I was losing about 1.2 dKH per day. I use BRS GFO, but since I don't have a reactor, I use my canister filter as my chemical filter (for both GFO and carbon). I fill 2 bags with GFO and put it in my filter. I know that's way more than I need, but this way, I don't need to change it out for 6 weeks or so. My Phosphates are always at zero. Could this be the reason for losing 1.2 dKH per day, or is it because of the corals, inverts, and coralline in my tank?

Thanks [emoji846]

 

[CodyRVA]

My guess is a testing error or expired kit resulting in a dKH of 4.0. I would confirm with several kits before making any changes. IME GFO can affect ALK, but not directly. If you strip your system of nutrients, this will affect growth rates of your coral, thus affecting consumption rates and causing your ALK to increase. I can't say i've ever seen GFO affect ALK directly, let alone making it drop, just my experience.

I would make small changes and assess the impact before getting too crazy, especially in regards to ALK. I find it very unlikely your ALK is that low, if you do have a testing error and you raise your ALK, you may end up raising it far higher than you had intended.

Lastly, adding more GFO to your system at one time so you don't have to change it as often is not the proper approach. You will strip your system of PO4 in the process which will affect your coral. GFO is not something you can go heavy on in hopes of saving time later. Yes, your GFO will definitely last longer, but it will not end in the way you wanted it to.

 

[GoPitt88]

My guess is a testing error or expired kit resulting in a dKH of 4.0. I would confirm with several kits before making any changes. IME GFO can affect ALK, but not directly. If you strip your system of nutrients, this will affect growth rates of your coral, thus affecting consumption rates and causing your ALK to increase. I can't say i've ever seen GFO affect ALK directly, let alone making it drop, just my experience.

I would make small changes and assess the impact before getting too crazy, especially in regards to ALK. I find it very unlikely your ALK is that low, if you do have a testing error and you raise your ALK, you may end up raising it far higher than you had intended.

Lastly, adding more GFO to your system at one time so you don't have to change it as often is not the proper approach. You will strip your system of PO4 in the process which will affect your coral. GFO is not something you can go heavy on in hopes of saving time later. Yes, your GFO will definitely last longer, but it will not end in the way you wanted it to.

I first used a new Red Sea Reef Foundation Pro kit, and the Alkalinity was below 5.3 dKH (which is the low end of the scale). So then I bought a Hanna Checker, and it read 4.0. That's when I slowly started to elevate it. Both kits read pretty close. My corals look good from what I can tell, but sounds like they probably could do better since I have no point of reference. My birdsnest grows SO fast! Anyway, I'll start reducing how much GFO I use. My nitrates are between 1 and 5 (not quite yellow, but a little orange). What should I shoot for with regards to Phosphates? I have a Hanna Checker for Phosphates as well.

 

[CodyRVA]

I first used a new Red Sea Reef Foundation Pro kit, and the Alkalinity was below 5.3 dKH (which is the low end of the scale). So then I bought a Hanna Checker, and it read 4.0. That's when I slowly started to elevate it. Both kits read pretty close. My corals look good from what I can tell, but sounds like they probably could do better since I have no point of reference. My birdsnest grows SO fast! Anyway, I'll start reducing how much GFO I use. My nitrates are between 1 and 5 (not quite yellow, but a little orange). What should I shoot for with regards to Phosphates? I have a Hanna Checker for Phosphates as well.

Do you do water changes and if so how much and what salt? What's your CA and MG at? What are you using to maintain your parameters: doser, reactor, etc?

Nutrient levels are relative to your ALK, so with that low of ALK you'll want low nutrients. You can keep high or low ALK, but your nutrients need to follow. If you run high nutrients you need higher ALK. I wouldn't go above 8.0 dKH if you're going to maintain 1-5 ppm NO3 and 0-.2 ppm PO4.

 

[GoPitt88]

Do you do water changes and if so how much and what salt? What's your CA and MG at? What are you using to maintain your parameters: doser, reactor, etc?

Nutrient levels are relative to your ALK, so with that low of ALK you'll want low nutrients. You can keep high or low ALK, but your nutrients need to follow. If you run high nutrients you need higher ALK. I wouldn't go above 8.0 dKH if you're going to maintain 1-5 ppm NO3 and 0-.2 ppm PO4.

I do weekly 10% water changes religiously. I use Instant Ocean Reef Crystals. On Saturday, I measured 430 calcium, 1500+ magnesium with Alkalinity of 7.7.

 

[Dana Riddle]

It sure can. See here:
http://www.advancedaquarist.com/2011/6/review

 

[roberthu526]

Personal experience is if everything is thriving, don't chase numbers. If you want, do it extremely slow.

 

[MIKE NY]

It sure can. See here:
http://www.advancedaquarist.com/2011/6/review

X2....it's been my experience as well. I thought it was the miricle additive when first introduced. I still use it sparingly, but installed a large fuge.

 

[reeferfoxx]

It sure can. See here:
http://www.advancedaquarist.com/2011/6/review

Your article here saved my tank once! Thank you for that!

 

[GoPitt88]

X2....it's been my experience as well. I thought it was the miricle additive when first introduced. I still use it sparingly, but installed a large fuge.

Can it explain a drop of 1.2 dKH per day?