Flow Questions

Jason boles · Sep 20, 2018

I have a 15 gallon Fluval Flex aquarium with stock nozzles and a tunze silence that pump out at 211 gph.

I had also purchased a tunze nanostream, but it seems when its running I have way too much flow...

Thinking that it is either fine, or maybe I should purchase a higher GPH pump... not sure. The hammer coral very gently moves in the front and there seems to be some flow over the acans on the side. My brain coral is directly underneather the pwer heads, but still gets a bit of flow from them hitting the glass.

What are you guys thoughts, or experience?

Jason boles · Sep 20, 2018

Full Tank shot. The Ricordea doesn’t really move but it’s small. With the nanostream it’s skirt kinda blows up. You can see brain in back right corner reflecting off of glass.

Ron Reefman · Sep 21, 2018

You have a 15 gallon tank divided into 211gph pump means you are turning over the water in your tank about 14 times per hour. That isn't a lot, but on a small tank with just some frags it should be OK for now.

But typical reef tanks run between 20 and 60 turns per hour and some sps tanks turn up to 80 times. If your drain from the DT to the sump can handle more flow from the return pump, then a more powerful return pump could work. But it's not wise to push the drain to it's limit unless you have an emergency drain in case anything blocks the main drain or even restricts the flow a little bit, like a rouge snail or a small clump of algae.

The other option, and this is what I do in my 50g cube, is add wavemaker powerheads to the display tank. Current offers a good quality system that allows for up to 3 pumps on 1 control module. They are very highly adjustable in terms of how much flow you add, whether it's constant flow, pulsing, random etc. And they are controlled with a small remote. They offer 3 sizes and I'd recommend you get 2 of the smallest ones and add them to the back or sides of your tank. There are cheaper alternatives, but these are good pumps and the remote control has been a very nice feature that I use frequently.
https://www.saltwateraquarium.com/e...i06MGZtw4xukO-0m-iZQV98Ixf-wpFAgaAp8mEALw_wcB

The more random you can make the flow in your tank, the better the corals will do. Also, having water movement at the surface is the very best way to get gas exchange between the water and the air. That means getting C02 out of the water and oxygen into the water. A skimmer does this job OK, but waves at the water's surface is a lot better.

Jason boles · Sep 22, 2018

Thanks Ron!! I ordered just one with a controller. Gonna give it a whirl!

Katrina71 · Sep 22, 2018

Also look at Random Flow Generator nozzles. Pretty cool.

Jason boles · Sep 22, 2018

I thought of getting one of these. But was fearful it may push too much flow in one direction.

I’ll grab one and try it out. Worse case I won’t like it and go back to the other!!

I’m super confused on kalkwasser. When should one start dosing? Should I first see a dip in Ca levels, or does it just keep what I have steady??

Or should I only pay attention to alk? I may just be too early in my tank to be using up either in any way that requires supplementation yet.

Sigh. I find so much info on Kalk, but none directing me when I should begin using it.

Ron Reefman · Sep 23, 2018

Jason, kalk and dosing both accomplish the same thing, they keep your Ca and alk at the levels your tank needs to be healthy. But if you don't have many lps or sps corals you may not need to do anything. Early in a tank's life just doing water changes will keep the Ca, alk and Mg up to healthy levels. When you start to see Ca and/or alk going down even with water changes, then you need to start adding Ca and alk either by kalk or dosing. IMHO dosing is easier and safer. My best guess is until you have a quite a few lps and sps corals you won't see much of a dip in Ca or alk. Especially if you do a 2 to 5 gallon water change every week or two.

I have a 50g cube DT with a 40g sump/refugium. It's full of zoas and anemones which really don't use much Ca or alk. I do have a couple of lps and a handful of sps corals along with a lot of snails, a flame scallop, a few feather dusters, an emerald crab and some porcelain crabs which do all use some Ca and alk to build skeleton or shell. So I test Ca and alk every Monday and usually need to dose about 30-50ml of Ca to get from 400 to 425 and roughly 50-75ml of alk to get from 7 to 9dKH. I don't use dosing pumps for an amount this small, I just dose by manually every Monday. Ca goes in the tank easy. Alk I have to feed in very slowly and right where a pump is moving a lot of water otherwise it will precipitate out. I get a little white cloud right in the area where I'm pouring it in, but the pump blows it out and it disappears as it is mixed with the tank water.

BTW, I use a sidewalk ice melting product called Dowflake to raise my Ca and swimming pool product (soda ash or sodium carbonate) to raise alk. You can also use sodium bicarbonate which is just ordinary baking soda. I used to have 4 tanks (600 gallons of saltwater) in the house before I downsized. So rather than buying Ca and alk products from an LFS or even Bulk Reef Supply, I bought serious bulk (25 and 50 pound bags) and very generic products instead. I used to go through a 50 pound bag of Dowflake in less than a year. It cost me less than $20. The same 50 pounds of Ca from BRS would cost me nearly $150. Yikes! And the savings in alk is almost the same. Oh, and after using these generic chemicals for over 10 years, no issues whatsoever! Randy Holmes Farley, in the R2R Chemistry Forum, was who recommended them back when he was on the other website. And most chemistry calculators will list Randy's Recipe along with all the other brand name Ca and alk additives.