70W MH in stock Nano Cube!!

[artarmon42]

I posted this morning's photos here.

[artarmon42]

It's been 2 days now, so time to report my findings.

 

Day 1: Ambient was between 68.4 to 73.2 (pretty cool day). Water temp ranged from 78.2 to 83.4. When I came home from work, it was 81.5 (which would have been under 80 with the front flap open).

 

Day 2: Ambient was between 70.1 to 78.4 (the high was the highest since I started recording). Water temp ranged from 77.9 to 83.5. When I came home from work, it was 81.1.

 

Observations:

1) The max water temp is 1-2 degrees higher than with the front flap open. Higher than I'd like, but still acceptable.

2) After the photo period, the water temp doesn't drop as quickly as with the front flap open.

3) The water temp does however drop (overnight) low enough for the heater to kick in.

 

Conclusions:

1) Rear vents are not as efficient as having the front flap prop'd up. However it is more aesthetically pleasing (to me).

2) Rear vents are still better than no venting at all.

3) The fact that the overnight temps does drop to the "previously recorded lows", would seem to indicate that there is sufficient venting and time-lapse for the tank to cool down completely before the next photo period.

 

Hypothesis:

1) I'm pretty certain that OVERALL the 70W MH doesn't heat the tank up anymore than cramming the hood full of PCs.

2) I suspect that without the stock reflector and better fans, this hood actually cools better than a stock hood (with or without additional PCs).

3) I suspect that the 70W MH heats the water up marginally more than 100W+ of PCs. Perhaps MH-experts like jmt or others can verify/correct this suspicion.

4) I suspect that the rear vent idea will benefit any Nano Cube, as it compensates for the lack of venting in th area between the splashguard and the water surface.

5) I'm pretty certain I can superglue a scroll fan to blow air into one of the vents, to aid air circulation. Will have to try that this weekend.

[ccjung]

I think the part that you havent really addressed is the fact that with heat you are dealing with several mechanisms for heat transfer.

 

Convection (the heat of the water heating your tank)

Conduction (the effects of the heatsheild and surrounding areas in contact with the bulb)

Radiation (the effects of the lights ability to heat the water without going through any physical medium)

 

With MH & PC you have convection from the heat between the splashguard and the water (what the vent/feeding door reverses).

 

With MH & PC you also have conductive heating of the hood and splashguard (temps on PCs are however, much much lower than the MH).

 

With MH you have radiation, where in contrast the PCs emit very little infrared light. The only substantial radiative heat transfer from PCs comes from the Splashguard being hot and emitting infrared, so if you keep the splashguard cooler, you keep the infrared emission.

 

Being an owner of both the "crammed" PC versions at 102-126w and also my 70w MH, i can safely say that:

 

"1) I'm pretty certain that OVERALL the 70W MH doesn't heat the tank up anymore than cramming the hood full of PCs. "

 

Is incorrect. Most PC owners experience temps only 1-2 F above ambient, whereas our MHs (notice i said OUR) run 6-12F above ambient.

 

I think that our biggest heat contributor comes from teh IR spectrum emitted by the MH.

 

In comparison i put my temp gun on the splashguard of a Mikeguerrero edition vs. my 70w MH.

 

mikeg- 102w (up front) - Max Temp 122F

ccjung - 70w MH - Max Temp 150F (in 1 small patch). Rest of the splashguard at 100-120s.

 

This is going to perpetuate the debate, but if you are talking about how much intensity can fit in a cube, the PC will win hands down until you get the 150 in there (yummy!!).

 

Spectrum is a different story... Because of the halogens in the MH, you get all three spectrum bands with them "dialed" in for coral. Your Montis and other SPS will "love" the MH more and will thrive under MH vs PC. Color retention is negligible, but there is a definate change in the rate of growth.

 

Its the balancing act of the heat and light output. I would be very careful about running without (if not the stock, some sort of) heatshield, as the conduction of heat from the bulb to the lampholder may melt/warp the hood over time.

 

Hope this helps..

 

Chris

[artarmon42]

Good points Chris.

 

We've talked, so I'm sure you know that I was comparing MH with extra PCs, as opposed to making them competing (each has it's use and benefits). My comment about "cramming" was related to the density vs free flow of air and the hood's actual temp. Unless the hood is so hot that things warp/melt, I believe the hood's temperature is relatively inconsequential to the heating of the water temperature.

 

I believe that the actual heating of the water temp (which is really what we most care about) is primarily caused by the heating of the water from the MH "spectrum". And that dissipation of the heat is hampered (and potentially adversely affected) by the lack of venting between the splashguard and the water surface.

 

Increasing airflow in that area should help dissipation, to be as good if not better than opening the front flap.

[ccjung]

Sorry if the tone seemed as if i was responding to the "cramming" thing. I think what i should have said is that irrespective of the heating of air, the MHs spectrum emits radiation (which would also transfer heat in a vacuum), so cooling the hood wont help reduce this amount of energy.

 

In the PC the bulbs are emitting mostly in the visible light range (little to no UV or IR). A good example is with reptiles where they make "infrared & UV" specific PCs.

 

I think that if you put extra PCs in with your MH, you will as you say, notice an "inconsequential" increase in heat, since you have good venting.

 

You are absolutely right when you say that extra venting will help the tank dissipate its newly added IR energy and I think that venting the hood is a great idea.

 

Since most of us nanocube owners fell in love with the clean lines, rear vents make lots of sense. Did you mention that you had put scroll fans on the back? That should help lots, or maybe even some very small fans (25mm or so) mounted back there can help get some heat out.

 

Also, are you running a heater? If you are, i think the baseline comparison of heat should be taken from that value (the heaters set point) instead of ambient.

 

The ambient will only affect how the glass dissipates heat, since its a matter of convection between the glass and the room.

 

The real big fear is when the ambients get up in the high 70s, where the glass will no longer be able to dissipate heat into the room(cool the tank), but instead gets heated by the room.

 

I think that we are pushing the envelope yuen, and i like everything you are doing.

 

Theres a reason why even big tanks with halides hung 6inches to a foot above the tank still have heat issues. Lol.

 

You my friend, are a nano-pioneer,

 

Cheers

 

Chris

[ccjung]

Also on that note, i think the only way we can survive summer if ambients get too hot and chillers are unavailable (the TEC is STILL in testing.), is to wrap the darned things in aluminum foil. Lol.

 

Chris.

[artarmon42]

No worries Chris. I think we pretty much see eye-to-eye and have helped each other out. Just didn't want anyone else reading to think that there was some kind of competition going on here ???

 

I am going to try to get that scroll fan setup this weekend. Will report back when I have enough data.

 

As for the cooling in summer, I have temporarily abandoned the NanoIceProbe idea. I am going to fall back to 2 circumstantial points:

1) My house will never get much above 80 (young kids, house A/C). 80 would still be below the water temp, allowing for natural heat dissipation.

2) Many reefers rely on fans blowing across the water to cool without needing to resort to a chiller. If I can get the scroll fan going, it should achieve similar results.

 

Points (1) and (2) together should (hopefully :angel: ) be able to get me through summer :-*

[artarmon42]

Oh and I'm reporting ambient, because with the front flap open or fans forcing air through the rear vent, ambient does have a noticeable impact to cooling. In that on cooler days, the day's high doesn't get as high and cools down quicker.

[artarmon42]

So I finally got around to install the rear fan today.

 

Luckily the scroll fan fits (reasonably) well in the rear vent I cut previously.

 

The fit isn't perfect, but the gaps are close enough to fill with epoxy...

 

Using the epoxy that I used to glue the MH bracket to the hood, I glued the fan and filled in the gaps for an "air tight" seal.

 

Here is the hood screwed back on top of the Nano Cube.

 

The fan blocks the hood opening all the way back, which makes is a little hard (but not impossible) to screw/unscrew the hinges. But doesn't impact the "normal" positions for the arms that hold the hood up.

 

Here's what it looks like from the side:

And from the top:

 

I wired the scroll fan with the two top exhaust fans, which is set to 9V.

[artarmon42]

Background: By the time I got around to installing the rear fan, I was already 2 hours into the photo period. So the tank was already "hot".

 

Here's the first shot, after I put the hood back on, before I fired up the MH.

 

15 minutes later, there is no noticeable change in temperature. Would normally be at least +0.2 degrees by now.

 

More than 2 hours later, the temperature is still rock solid.

Note that the ambient temp is increasing (point is that the air blowing in is getting hotter).

 

Interestingly after a "long" time (nearly 5 hours into the photo period), the temp takes the first dip.

 

After the photo period ends (at 2pm), the temp "rapidly" (drops 1 degree in 30 minutes) to reach the stable point (where the heater kicks in).

 

Other findings/thoughts:

1) It seems that the fan is able to not only counter the MH heat, but also reverse it.

2) Today's experiment, with the MH having heated up the tank for 2 hours before the fan started, shows it's cooling power.

3) Tomorrow, when I go through a full photo period with the fan on from the start, the temp should not rise at all.

4) There is ZERO condensation so far: for the 5 hours of MH, and the 2 hours since the MH turned off. The real test will be overnight, and I'll report finding tomorrow.

5) Although the lack of condensation is a symptom, I have not noticed any evaporation. Visually my water level has remained constant and the SG reading on my Hydrometer remains the same.

[Esper]

so does the scroll fan blow cool air in or hot air out? and how noisy is it?

[SeanCallan]

Those fans blow cool air INTO the hood.

 

Awesome, can't wait to hear more!

 

Just think, if you could get 2 fans back there, you could go 150w

[artarmon42]

It blows room temperature (ambient) air in.

 

Putting MH in the stock hood requires 4 more powerful fans in the hood. Those fans, are louder than the stock fans, but not significantly more so.

 

The scroll fan is probably slightly louder than one of those new fans (because it's out in the open and not enclosed in the hood).

 

All up, it's quieter than my AC500 HOB filter.

And heavenly compared to my Remora

[artarmon42]

Heh, yeah I think 150W is definitely do-able with this configuration. But I think 70W is enough for now.

 

I just comissioned a 20G custom nano with 150W.

 

This one is going to be relegated to my Onyx pair + anemone. 70W MH for an anemone... oh it's going to love me

[SeanCallan]

Keep us updated!

 

I can't wait to get my cube (24x24x24) under construction this summer. I'm lighting the whole thing with 1 250w, don't want to deal with the increased heat of a 400.

 

Let me know how your 20 goes

[artarmon42]

Overnight low water temp was 79.0.

My heater kicks in around that, and usually keeps the water around 79.4-79.6.

 

Right now, 4 hours into the photo period, water temp is 80.2.

 

I'm pretty certain that the "rise" in temperature is fully attributed to the fact that sun is streaming in from the window. My temperature monitor (measuring ambient) was reading 81, until I moved it into the shade (which now correctly reads 75.1). It is good to know that the rear vent/fan is able to compensate for heat from direct sunlight.

 

Evaporation is another issue. While I didn't notice a change in the water level yesterday, it was noticeable this morning. Top up required ~1/2 a quart (~0.1 of a gallon). I'm going to have to go out and buy another adapter for the rear fan and set it to only come on when the MH fires up, to minimize top off.

 

Interestingly, there was no condensation on the splashguard or around the tank, so I'm not sure where that water is going to

[sterling18]

artarmon42,

 

Quick question, did you try using a screen when you first started to use your light also? I remember that you started with a short photo period and then extended it.

 

My concern is that I have a yellow leather and I'm worried that it might get burned? I'm really to take the leap into the MH.

 

tks

[SeanCallan]

MH light can be intense for quite a few soft or LPS corals. You need to determine if any of these are in your tank before you jump to using MHs.

 

Most of the livestock in his tank are SPS and a clam, both do wonders under MH.

 

MHs may just not be for some people. I'd try and talk to more people who have Yellow Leathers and see what a MH that close would do to it.

[artarmon42]

Acclimation to MH is pretty important to avoid frying anything.

 

They say the full spectrum of MH will reach down 24" of water. So in a Nano Cube, even the corals located at the bottom of the tank is in the "full glory" of MH light.

 

The "good" news is that the MH is reasonably close to the top of the water. That way, high rockwork end up creating shaded areas at the bottom.

 

People normally recommending acclimating corals (to MH) by putting it at the bottom of the tank and then slowing moving it upwards to its final location. In the Nano Cube MH setup, I'd recommend taking an extra step and putting it in a SHADED area at the bottom first.

 

 

According to Liveaquaria (first place I checked), Yellow Fiji Leather Coral is medium to high lighting. Sounds like, with proper acclimating, it should be fine.

[artarmon42]

Update for today:

1) Top off required another half-quart this morning (ah, consistency!)

2) Overnight low water temp of 79.4, high water temp was 81.0 (presumable towards end of photo period yesterday).

3) Yesterday was a hot day in San Jose. Ambient reached a high of 78 in the afternoon. No noticeable effect on the cooling of the tank (I suspect the tank's heater was on most of the day).

4) Checked the tank this morning and noticed some salt creep (at the waterline). I guess this is the price to pay for air cooling the tank. Pretty easy to fix, but will need to pay attention to SG level in the next few days.

 

Today I re-wired the rear vent/fan to the same timer as the MH. That way, it'll only be on as needed and minimize evaporation/salt creep.

[TiGs]

Originally posted by SeanCallan

Those fans blow cool air INTO the hood.

 

Just think, if you could get 2 fans back there, you could go 150w

 

Nice DIY artarmon

 

MH should be typically be setup 8"-12" above the water surface. Having 150W that close to the water is pushing it. your asking for your corals to get burned and SPS colors will change in a bad way to more of tan yellow color instead of a green for example. 70W might be ok being that low but it will be a bigger risk using a 150W

[artarmon42]

Thanks for the feedback TiGs. Always good to get expert advice/opinion!

 

Update since the re-wire:

1) As I had hoped and expected. top off required less than one-tenth of a quart this morning. The reduction in evaporation is due to timing the rear vent/fan to only come on when the MH fires up. The top off is relatively so little, I think I could conceivably do a manual top off once every few days.

2) Overnight low water temp was 79.3, high water temp was 80.8.

3) Yesterday was a cooler day in San Jose, so wasn't a real "stress test" of temperature control.

4) Because the rear vent/fan is synchronized with the MH, the water temp no long rapidly cools when the MH turns off. I guess avoiding rapid temperature changes is better for the tank.

 

Overall, I feel that this mod is pretty much done.

I'm going to monitor it for a couple more days, and then write up a summary (because of the various changes applied during the course of the experiment).

The real test will come in another few months (summer!), so I'll do a followup status report at that time.

[artarmon42]

For those who have been following the thread...

 

My frogspawn never did recover.

Above 3 days ago, I noticed that one head had completed receeded and that the other head was now showing the same "deflated" symptoms.

(I fully attribute the damage/death to my Onyx's rough handing)

 

Anyway, I removed the frogspawn, and within a day the pair had found a new host in my Fugia Plate.

 

Here are some cute shots:

 

If you look carefully, the female (in the background) is starting to get color between the second and third bar.

[SeanCallan]

Awesome pictures man

 

I got my new DX hood in and just need some rock now. I'm hoping for now 48w of PC will do just fine. I don't think I'm going to try and upgrade my lighting in my cube. I just got a fanastic quote from a builder and till spend my money on my 60g cube instead

 

Great thread though and I will continue to read!

[MadTownMax]

excellent work atarmoon - I don't know what your living situation is, but if you have your own apartment you could always try cranking up the heat (or getting a space heater) and bringing your room up to a maximum temperature that you expect to hit this summer.

 

It would be good to do on a day that you have a lot of time to monitor so that you can solve any problems that arise, instead of a badly-timed hot day in the summer when you might be busy w/ something else.

 

I really am pulling for you though, as if you can do this w/ your tank, a 70W retrofit for my 24 should be a piece of cake

 

ever thought of using a simple Ranco digital Temperature controller to monitor your tank's temperature and to kill the Halide if it raises the temperature too much?

 

I'm thinking if I ever get the cajones to do this mod I will probably be investing in one as a safety back-up

 

-Nick