Coralline Algae & Water Parameters

[Jivenjune]

I've recently swapped out my crushed coral substrate for a mixture of oolitic and reef grade aragonite based sand. I do not have any corals. It is a fish only tank, and the sand bed is approximately 2 inches deep.

Currently, my water parameters are listed as the following:

Ammonia: 0
Nitrite: 0
Nitrates: 0-5 (I've done some large water changes recently due to sand cloudiness, so it's nearly undetectable).
Phosphates / Silicates: I'm not sure what these are at, but I'm using a fairly large amount of SeaChem SeaGel (activated carbon/phosphate-Silicate magnet) to help keep these two down.
Alkalinity/DKH: 10 or 179 GH/KH PPM.
Calcium: 420-440 PPM.

Though I have supplements for both calcium and alkalinity (SeaChem), I have not used either to obtain my current water parameters. My water seems to naturally be at these levels. Should I be increasing my alkalinity or calcium to encourage coralline algae growth?

Also, I was wondering if I would need to eventually supplement my aquarium with doses of alkalinity and calcium, or would my sand bed and live rock provide the necessary calcium/alkalinity to support my coralline algae?

[Mek0ng]

How was the calc and alk before the sand bed change?

I would guess that there was a good ammount of 'dust' in the sand that has/is buffering the tank and will start to drop off as the tank ages.

You will in time find a equilibrium in your tank where you know about how much 2 part (or what ever dosing method) that you need.

How do you like seagel? Do you run it in a reactor?