2 questions on ammonia and macro-algae

[KotyH]

My aquarium has been cycling for 14 days now and I have a Seachem ammonia hanging detector that reads 0.05 ppm and my Salifert reads between 0.25 to 0.5 ppm. (No3 is 25-50 ppm both today). From what I read the Seachem is considered unreliable however the Salifert colors are very hard to distinguish at the lower concentrations (Or am I getting too old?).
My second question is regarding the Chaeto that I added about 4 days ago (Light is Kessil H80 on for 16h/day). Do I need to supplement it with Iron immediately for it to start growing/"working" or leave it for later stages after I see actual growth?
Thanks in advance
Koty

 

[Oldreeferman]

Cheato needs a constant nutrient supply to grow, nitrates etc. in an established tank. Probably not necessary atm until you have your fish introduced then it will help to control the DT algae ugly phase somewhat while placed in the sump with a night light.
Have you checked for nitrites yet? Once you get readings from nitrites to nitrates ammonia is no more an issue.

 

[KotyH]

Thanks for the reply
I do not check NO2.
When the ammonia started dropping (2 days ago) I added one black molly after a long acclimation to SW. It looks quite active and i feed it twice daily with a bit of dry food and a bit of frozen bloodworms. Sump is lit for about 16h when display tank lights are off. The NO3 went up and stabilised at 25ppm although today it went a bit higher. I expect that once the Cheato kicks-in it will "join" the bacteria to reduce Amm, NO2 and NO3.

 

[KotyH]

Regarding the Seachem alert...

Regarding the Seachem alert...

Ok, found the answer to the difference. I guess its well known but I will address it anyway: Seachem only measures the toxic neutral NH3 which can penetrate cell membranes while the kits measure total ammonia NH3/NH4+. In basic seawater (~8.5) the steady state between both types comprises much more NH4+ than NH3. So multiplying the Seachem by 5-6 gives a (very) rough estimation of the total ammonia. This is not very accurate as at this pH range the ratios change significantly (At pH 9.26 reaches 1:1 ratios also known as pKa)