Low Alkalinity

[spamvicious]

Been running my tank for 10 weeks. Three weeks ago my alk was 5, I was advised that it was maybe the test kit I used as it seemed low. I changed the test kit and got a result of 6.8. I tested again today and it’s 4.5.

I have two small coral frags but otherwise just a few fish and cuc. I get both my ro water and pre mixed salt water from the local fish store which is well established and has a good reputation.
What should I do?.

 

[Cali Reef Life]

I would check your salinity level in your tank. We also don't know how long in between test it was. If your doing weekly water changes it should stay near the same level with only 2 frags. Make sure salinity is around 1.25. Any time I get an odd number I always retest because sometimes theres a bubble or something went wrong.

 

[gbroadbridge]

Been running my tank for 10 weeks. Three weeks ago my alk was 5, I was advised that it was maybe the test kit I used as it seemed low. I changed the test kit and got a result of 6.8. I tested again today and it’s 4.5.

I have two small coral frags but otherwise just a few fish and cuc. I get both my ro water and pre mixed salt water from the local fish store which is well established and has a good reputation.
What should I do?.

First check salinity as that affects everything else.

Use a salifert ALK test kit.

If that is normal, go to the pantry and grab some baking soda and use that to increase Alk.

The calculator is here

Reef Chemistry Calculator

 

[NanoCrazed]

Been running my tank for 10 weeks. Three weeks ago my alk was 5, I was advised that it was maybe the test kit I used as it seemed low. I changed the test kit and got a result of 6.8. I tested again today and it’s 4.5.

I have two small coral frags but otherwise just a few fish and cuc. I get both my ro water and pre mixed salt water from the local fish store which is well established and has a good reputation.
What should I do?.

If your 2 coral frags are softies...which I'm guessing is the case given how young your tank is, then I would do nothing. Alkalinity and calcium are less important, if so.

 

[spamvicious]

Checked the salinity and it’s 1.25. I’m using a salifert test. I tested yesterday evening and it was 4.5 and tested just now (11:30am) and it’s 4.8. The two frags I have are gps and xenia.

 

[gbroadbridge]

Checked the salinity and it’s 1.25. I’m using a salifert test. I tested yesterday evening and it was 4.5 and tested just now (11:30am) and it’s 4.8. The two frags I have are gps and xenia.

When you say 1.25 for salinity, can you check. Noramlly it should be 1.025

 

[Garf]

Checked the salinity and it’s 1.25. I’m using a salifert test. I tested yesterday evening and it was 4.5 and tested just now (11:30am) and it’s 4.8. The two frags I have are gps and xenia.

Assuming your not reading the syringe value wrong, can you test some fresh made saltwater?

 

[spamvicious]

When you say 1.25 for salinity, can you check. Noramlly it should be 1.025

Sorry yes typo it’s 1.025. I have a fluval salinity hydrometer in the tank but also check regularly with a refractometer.

 

[spamvicious]

Assuming your not reading the syringe value wrong, can you test some fresh made saltwater?

Yeah I checked the instructions for reading the syringe as there is always the space for air in it.

 

[spamvicious]

Assuming your not reading the syringe value wrong, can you test some fresh made saltwater?

I’ll check when I’m back home and post pictures of the syringe to make sure I’m reading properly.

 

[Garf]

Yeah I checked the instructions for reading the syringe as there is always the space for air in it.

Was more concerned with an unintentional addition of a step, tbh. The reading is taken from the amount left in the syringe, not the amount of solution used.

 

[gbroadbridge]

Sorry yes typo it’s 1.025. I have a fluval salinity hydrometer in the tank but also check regularly with a refractometer.

In that case I would use some sodium bicarbonate (Baking soda from the Pantry) to boost the Alk to about 8 dkH

Use this calculator to work the correct dose.

Reef Chemistry Calculator

 

[spamvicious]

Was more concerned with an unintentional addition of a step, tbh. The reading is taken from the amount left in the syringe, not the amount of solution used.

No I follow the instructions word for word and with everything lol.

 

[Rmckoy]

A Alk measurement that low is odd and I would only suspect testing error . Either with the test itself or the operation performed . More likely the test itself .

take a sample of water to a reputable lfs and have it tested .
it is very possible the lfs selling the premixed salt water has extremely low alkalinity or low salinity to try to cut corners and save money .

 

[spamvicious]

A Alk measurement that low is odd and I would only suspect testing error . Either with the test itself or the operation performed . More likely the test itself .

take a sample of water to a reputable lfs and have it tested .
it is very possible the lfs selling the premixed salt water has extremely low alkalinity or low salinity to try to cut corners and save money .

Yeah when I did the initial test with the Red Sea kit people told me it must be a dodgy batch of tests as it was so low so I bought the salifert test. Which has given the same result. I will test again and show pictures of the syringe and the sample and if it is still low I will send off for a test.

 

[Mr. Mojo Rising]

I would suggest to make a rodi unit a top priority, and then you can mix your own saltwater, and you can choose a salt with parameters that suit you. Take control of your tank right from the begginning, and the beginning is water and salt. Rodi unit is as important as the lights.

Not to mention the additional benefits of being able to make saltwater whenever you want, and not having to transport 50 lbs buckets of saltwater that can splash or spill anywhere.

 

[spamvicious]

I would suggest to make a rodi unit a top priority, and then you can mix your own saltwater, and you can choose a salt with parameters that suit you. Take control of your tank right from the begginning, and the beginning is water and salt. Rodi unit is as important as the lights.

Not to mention the additional benefits of being able to make saltwater whenever you want, and not having to transport 50 lbs buckets of saltwater that can splash or spill anywhere.

That’s not an option as I live in rented accommodation which is a first floor flat. The water pressure is terrible and there is also no where I could run the filter.

 

[NanoCrazed]

Given all you have is gsp and xenia, I definitely wouldn't stress too much. Practical vs ideal, imo.

Should you want to practice to get things dialed in for future additions, then perhaps maybe worth the effort.

Rather than salifert or Redsea, suggest getting a Hanna checker to simplify things a bit.

An Alk value of 5 is not unreasonable for premade saltwater. After it sits for awhile, the alk tends to drop to about 5, even if I start higher on fresh made SW. I always test and adjust my alk to match my tank before adding as I keep fairly sensitive sps and the like. Otherwise, I wouldn't bother.

As mentioned earlier, if you need to adjust alkalinity, use baking soda or soda ash (baked baking soda, diy). Use a reef chemistry calculator to figure how much you need to add for your given volume.

My go to calculator: https://reef.diesyst.com/chemcalc/chemcalc.html

 

[spamvicious]

Ok so I tested the pre mixed sw I have and it is showing as 0.50 (7.7 dkh) When I tested the tank water again it came up as 0.68 (4.8 dkh). Below are images of the syringes to check I’m reading it properly. First is saltwater, second is tank water.

 

[Garf]

Ok so I tested the pre mixed sw I have and it is showing as 0.50 (7.7 dkh) When I tested the tank water again it came up as 0.68 (4.8 dkh). Below are images of the syringes to check I’m reading it properly. First is saltwater, second is tank water.

Yep, that looks right.